Authors Style Guide

This page presents design and layout guidelines for Angular documentation pages. These guidelines should be followed by all guide page authors. Deviations must be approved by the documentation editor.

Most guide pages should have accompanying sample code with special markup for the code snippets on the page. Code samples should adhere to the style guide for Angular applications because readers expect consistency.

For clarity and precision, every guideline on this page is illustrated with a working example, followed by the page markup for that example ... as shown here.

followed by the page markup for that example ... as shown here.

Doc generation and tooling

To make changes to the documentation pages and sample code, clone the Angular github repository and go to the aio/ folder.

The aio/README.md explains how to install and use the tools to edit and test your changes.

Here are a few essential commands for guide page authors.

1. yarn setup — installs packages; builds docs, stackblitz, and zips.

2. yarn docs-watch --watch-only — watches for saved content changes and refreshes the browser. The (optional) --watch-only flag skips the initial docs rebuild.

3. yarn start — starts the doc viewer application so you can see your local changes in the browser.

4. http://localhost:4200/ — browse to the app running locally.

You can combine yarn docs-watch and yarn start into one command with yarn serve-and-sync.

Guide pages

All but a few guide pages are markdown files with an .md extension.

Every guide page file is stored in the content/guide directory. Although the side navigation panel displays as a hierarchy, the directory is flat with no sub-folders. The flat folder approach allows us to shuffle the apparent navigation structure without moving page files or redirecting old page URLs.

The doc generation process consumes the markdown files in the content/guide directory and produces JSON files in the src/generated/docs/guide directory, which is also flat. Those JSON files contain a combination of document metadata and HTML content.

The reader requests a page by its Page URL. The doc viewer fetches the corresponding JSON file, interprets it, and renders it as fully-formed HTML page.

Page URLs mirror the content file structure. The URL for the page of a guide is in the form guide/{page-name}. The page for this "Authors Style Guide" is located at content/guide/docs-style-guide.md and its URL is guide/docs-style-guide.

Tutorial pages are exactly like guide pages. The only difference is that they reside in content/tutorial instead of content/guide and have URLs like tutorial/{page-name}.

API pages are generated from Angular source code into the src/generated/docs/api directory. The doc viewer translates URLs that begin api/ into requests for document JSON files in that directory. This style guide does not discuss creation or maintenance of API pages.

Marketing pages are similar to guide pages. They're located in the content/marketing directory. While they can be markdown files, they may be static HTML pages or dynamic HTML pages that render with JSON data.

Only a few people are authorized to write marketing pages. This style guide does not discuss creation or maintenance of marketing pages.

Markdown and HTML

While documentation guide pages ultimately render as HTML, almost all of them are written in markdown.

Markdown is easier to read and to edit than HTML. Many editors (including Visual Studio Code) can render markdown as you type it.

From time to time you'll have to step away from markdown and write a portion of the document in HTML. Markdown allows you to mix HTML and markdown in the same document.

Standard markdown processors don't allow you to put markdown within HTML tags. But the Angular documentation markdown processor supports markdown within HTML, as long as you follow one rule:

Always follow every opening and closing HTML tag with a blank line.

<div class="alert is-critical">

  **Always** follow every opening and closing HTML tag with _a blank line_.

</div>

It is customary but not required to precede the closing HTML tag with a blank line as well.

Title

Every guide document must have a title.

The title should appear at the top of the physical page. Begin the title with the markdown # character. Alternatively, you can write the equivalent <h1>.

# Authors Style Guide

Only one title (<h1>) per document!

Title text should be in "Title Case", which means that you use capital letters to start the first words and all principal words. Use lower case letters for secondary words such as "in", "of", and "the".

# The Meat of the Matter

Always follow the title with at least one blank line.

Sections

A typical document is divided into sections.

All section heading text should be in "Sentence case", which means the first word is capitalized and all other words are lower case.

Always follow the section heading with at least one blank line.

Main section heading

Begin a main section heading with the markdown ## characters. Alternatively, you can write the equivalent <h2> HTML tag.

The main section heading should be followed by a blank line and then the content for that heading.

## Sections

  A typical document is divided into sections.

Secondary section heading

A secondary section heading is related to a main heading and falls textually within the bounds of that main heading.

Begin a secondary heading with the markdown ### characters. Alternatively, you can write the equivalent <h3> HTML tag.

The secondary heading should be followed by a blank line and then the content for that heading.

### Secondary section heading

  A secondary section ...

Additional section headings

Try to minimize the heading depth, preferably only two. But more headings, such as this one, are permitted if they make sense.

N.B.: The Table-of-contents generator only considers main (<h2>) and secondary (<h3>) headings.

#### Additional section headings

  Try to minimize ...

Table of contents

Most pages display a table of contents (TOC). The TOC appears in the right panel when the viewport is wide. When narrow, the TOC appears in an expandable/collapsible region near the top of the page.

You should not create your own TOC by hand. The TOC is generated automatically from the page's main and secondary section headers.

To exclude a heading from the TOC, create the heading as an <h2> or <h3> element with a class called 'no-toc'. You can't do this with markdown.

<h3 class="no-toc">
This heading is not displayed in the TOC
</h3>

You can turn off TOC generation for the entire page by writing the title with an <h1> tag and the no-toc class.

<h1 class="no-toc">
A guide without a TOC
</h1>

Navigation

The navigation links at the top, left, and bottom of the screen are generated from the JSON configuration file, content/navigation.json.

The authority to change the navigation.json file is limited to a few core team members. But for a new guide page, you should suggest a navigation title and position in the left-side navigation panel called the "side nav".

Look for the SideNav node in navigation.json. The SideNav node is an array of navigation nodes. Each node is either an item node for a single document or a header node with child nodes.

Find the header for your page. For example, a guide page that describes an Angular feature is probably a child of the Fundamentals header.

{
  "title": "Fundamentals",
  "tooltip": "The fundamentals of Angular",
  "children": [ ... ]
}

A header node child can be an item node or another header node. If your guide page belongs under a sub-header, find that sub-header in the JSON.

Add an item node for your guide page as a child of the appropriate header node. It probably looks something like this one.

{
  "url": "guide/architecture",
  "title": "Architecture",
  "tooltip": "The basic building blocks of Angular applications."
}

A navigation node has the following properties:

• url- the URL of the guide page (item node only).

• title- the text displayed in the side nav.

• tooltip - text that appears when the reader hovers over the navigation link.

• children - an array of child nodes (header node only).

• hidden - defined and set true if this is a guide page that should not be displayed in the navigation panel. Rarely needed, it is a way to hide the page from navigation while making it available to readers who should know about it. This "Authors Style Guide" is a hidden page.

Do not create a node that is both a header and an item node. That is, do not specify the url property of a header node.

The current guidelines allow for a three-level navigation structure with two header levels. Don't add a third header level.

Code snippets

Guides are rich in examples of working Angular code. Example code can be commands entered in a terminal window, a fragment of TypeScript or HTML, or an entire code file.

Whatever the source, the doc viewer renders them as "code snippets", either individually with the code-example component or as a tabbed collection with the code-tabs component.

Code example

You can display a simple, inline code snippet with the markdown backtick syntax. We generally prefer to display a code snippet with the Angular documentation code-example component represented by the <code-example> tag.

Inline code-snippets

You should source code snippets from working sample code when possible. But there are times when an inline snippet is the better choice.

For terminal input and output, put the content between <code-example> tags, set the CSS class to code-shell, and set the language attribute to sh as in this example.

npm start

<code-example language="sh" class="code-shell">
  npm start
</code-example>

Inline, hand-coded snippets like this one are not testable and, therefore, are intrinsically unreliable. This example belongs to the small set of pre-approved, inline snippets that includes user input in a command shell or the output of some process.

Do not write inline code snippets unless you have a good reason and the editor's permission to do so. In all other cases, code snippets should be generated automatically from tested code samples.

Code snippets and code samples

One of the documentation design goals is that guide page code snippets should be examples of real, working code.

We meet this goal by displaying code snippets that are derived directly from standalone code samples, written specifically for these guide pages.

The author of a guide page is responsible for the code sample that supports that page. The author must also write end-to-end tests for the sample.

Code samples are located in sub-folders of the content/examples directory of the angular/angular repository. An example folder name should be the same as the guide page it supports.

A guide page might not have its own sample code. It might refer instead to a sample belonging to another page.

The Angular CI process runs all end-to-end tests for every Angular PR. Angular re-tests the samples after every new version of a sample and every new version of Angular itself.

When possible, every snippet of code on a guide page should be derived from a code sample file. You tell the Angular documentation engine which code file - or fragment of a code file - to display by configuring <code-example> attributes.

Code snippet from a file

This "Authors Doc Style Guide" has its own sample application, located in the content/examples/docs-style-guide folder.

The following code-example displays the sample's app.module.ts.

import { NgModule }      from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule }   from '@angular/forms';

import { AppComponent }  from './app.component';

@NgModule({
  imports:      [ BrowserModule, FormsModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

Here's the brief markup that produced that lengthy snippet:

<code-example
  path="docs-style-guide/src/app/app.module.ts"
  title="src/app/app.module.ts">
</code-example>

You identified the snippet's source file by setting the path attribute to sample folder's location within content/examples. In this example, that path is docs-style-guide/src/app/app.module.ts.

You added a header to tell the reader where to find the file by setting the title attribute. Following convention, you set the title attribute to the file's location within the sample's root folder.

Unless otherwise noted, all code snippets in this page are derived from sample source code located in the content/examples/docs-style-guide directory.

The doc tooling reports an error if the file identified in the path does not exist or is git-ignored.

Most .js files are git-ignored. If you want to include an ignored code file in your project and display it in a guide you must un-ignore it.

The preferred way to un-ignore a file is to update the content/examples/.gitignore like this:

content/examples/.gitignore

# my-guide
  !my-guide/src/something.js
  !my-guide/more-javascript*.js

Code-example attributes

You control the code-example output by setting one or more of its attributes:

• path- the path to the file in the content/examples folder.

• title- the header of the code listing.

• region- displays the source file fragment with that region name; regions are identified by docregion markup in the source file, as explained below.

• linenums- value may be true, false, or a number. When not specified, line numbers are automatically displayed when there are greater than 10 lines of code. The rarely used number option starts line numbering at the given value. linenums=4 sets the starting line number to 4.

• class- code snippets can be styled with the CSS classes no-box, code-shell, and avoid.

• hideCopy- hides the copy button

• language- the source code language such as javascript, html, css, typescript, json, or sh. This attribute only works for inline examples.

Displaying a code fragment

Often you want to focus on a fragment of code within a sample code file. In this example, you focus on the AppModule class and its NgModule metadata.

@NgModule({
  imports:      [ BrowserModule, FormsModule ],
  declarations: [ AppComponent ],
  bootstrap:    [ AppComponent ]
})
export class AppModule { }

First you surround that fragment in the source file with a named docregion as described below. Then you reference that docregion in the region attribute of the <code-example> like this

<code-example
  path="docs-style-guide/src/app/app.module.ts"
  region="class">
</code-example>

A couple of observations:

1. The region value, "class", is the name of the #docregion in the source file. Confirm that by looking at content/examples/docs-style-guide/src/app/app.module.ts

2. Omitting the title is fine when the source of the fragment is obvious. We just said that this is a fragment of the app.module.ts file which was displayed immediately above, in full, with a header. There's no need to repeat the header.

3. The line numbers disappeared. By default, the doc viewer omits line numbers when there are fewer than 10 lines of code; it adds line numbers after that. You can turn line numbers on or off explicitly by setting the linenums attribute.

Example of bad code

Sometimes you want to display an example of bad code or bad design.

You should be careful. Readers don't always read carefully and are likely to copy and paste your example of bad code in their own applications. So don't display bad code often.

When you do, set the class to avoid. The code snippet will be framed in bright red to grab the reader's attention.

Here's the markup for an "avoid" example in the Angular Style Guide.

<code-example
  path="styleguide/src/05-03/app/heroes/shared/hero-button/hero-button.component.avoid.ts"
  region="example"
  title="app/heroes/hero-button/hero-button.component.ts">
</code-example>

/* avoid */

@Component({
  selector: '[tohHeroButton]',
  templateUrl: './hero-button.component.html'
})
export class HeroButtonComponent {}

Code Tabs

Code tabs display code much like code examples do. The added advantage is that they can display multiple code samples within a tabbed interface. Each tab is displayed using code pane.

Code-tabs attributes

• linenums: The value can be true, false or a number indicating the starting line number. If not specified, line numbers are enabled only when code for a tab pane has greater than 10 lines of code.

Code-pane attributes

• path - a file in the content/examples folder
• title - seen in the header of a tab
• linenums - overrides the linenums property at the code-tabs level for this particular pane. The value can be true, false or a number indicating the starting line number. If not specified, line numbers are enabled only when the number of lines of code are greater than 10.

The next example displays multiple code tabs, each with its own title. It demonstrates control over display of line numbers at both the <code-tabs> and <code-pane> levels.

<h1>{{title}}</h1>
<h2>My Heroes</h2>
<ul class="heroes">
  <li *ngFor="let hero of heroes"
    [class.selected]="hero === selectedHero"
    (click)="onSelect(hero)">
    <span class="badge">{{hero.id}}</span> {{hero.name}}
  </li>
</ul>
<div *ngIf="selectedHero">
  <h2>{{selectedHero.name}} details!</h2>
  <div><label>id: </label>{{selectedHero.id}}</div>
  <div>
    <label>name: </label>
    <input [(ngModel)]="selectedHero.name" placeholder="name"/>
  </div>
</div>

import { Component } from '@angular/core';
import { Hero, HEROES } from './hero';

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'Authors Style Guide Sample';
  heroes = HEROES;
  selectedHero: Hero;

  onSelect(hero: Hero): void {
    this.selectedHero = hero;
  }
}

.heroes {
  margin: 0 0 2em 0;
  list-style-type: none;
  padding: 0;
  width: 15em;
}

{
  "scripts": {
    "start": "concurrently \"npm run build:watch\" \"npm run serve\"",
    "test": "concurrently \"npm run build:watch\" \"karma start karma.conf.js\"",
    "lint": "tslint ./src/**/*.ts -t verbose"
  }
}

Here's the markup for that example.

Note how the linenums attribute in the <code-tabs> explicitly disables numbering for all panes. The linenums attribute in the second pane restores line numbering for itself only.

<code-tabs linenums="false">
  <code-pane
    title="app.component.html"
    path="docs-style-guide/src/app/app.component.html">
  </code-pane>
  <code-pane
    title="app.component.ts"
    path="docs-style-guide/src/app/app.component.ts"
    linenums="true">
  </code-pane>
  <code-pane
    title="app.component.css (heroes)"
    path="docs-style-guide/src/app/app.component.css"
    region="heroes">
  </code-pane>
  <code-pane
    title="package.json (scripts)"
    path="docs-style-guide/package.1.json">
  </code-pane>
</code-tabs>

Source code markup

You must add special code snippet markup to sample source code files before they can be displayed by <code-example> and <code-tabs> components.

The sample source code for this page, located in context/examples/docs-style-guide, contains examples of every code snippet markup described in this section.

Code snippet markup is always in the form of a comment. Here's the default docregion markup for a TypeScript or JavaScript file:

// #docregion
... some code ...
// #enddocregion

Different file types have different comment syntax so adjust accordingly.

<!-- #docregion -->
... some HTML ...
<!-- #enddocregion -->

/* #docregion */
... some CSS ...
/* #enddocregion */

The doc generation process erases these comments before displaying them in the doc viewer. It also strips them from stackblitz and sample code downloads.

Code snippet markup is not supported in JSON files because comments are forbidden in JSON files. See below for details and workarounds.

#docregion

The #docregion is the most important kind of code snippet markup.

The <code-example> and <code-tabs> components won't display a source code file unless it has a #docregion.

The #docregion comment begins a code snippet region. Every line of code after that comment belongs in the region until the code fragment processor encounters the end of the file or a closing #enddocregion.

The src/main.ts is a simple example of a file with a single #docregion at the top of the file.

src/main.ts

import { enableProdMode } from '@angular/core';
import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';

import { AppModule } from './app/app.module';
import { environment } from './environments/environment';

if (environment.production) {
  enableProdMode();
}

platformBrowserDynamic().bootstrapModule(AppModule);

Named #docregions

You'll often display multiple snippets from different fragments within the same file. You distinguish among them by giving each fragment its own #docregion name as follows.

// #docregion region-name
... some code ...
// #enddocregion region-name

Remember to refer to this region by name in the region attribute of the <code-example> or <code-pane> as you did in an example above like this:

<code-example
  path="docs-style-guide/src/app/app.module.ts"
  region="class"></code-example>

The #docregion with no name is the default region. Do not set the region attribute when referring to the default #docregion.

Nested #docregions

You can nest #docregions within #docregions

// #docregion
... some code ...
// #docregion inner-region
... more code ...
// #enddocregion inner-region
... yet more code ...
/// #enddocregion

The src/app/app.module.ts file has a good example of a nested region.

Combining fragments

You can combine several fragments from the same file into a single code snippet by defining multiple #docregions with the same region name.

Examine the src/app/app.component.ts file which defines two nested #docregions.

The inner, class-skeleton region appears twice, once to capture the code that opens the class definition and once to capture the code that closes the class definition.

// #docplaster
...
// #docregion class, class-skeleton
export class AppComponent {
// #enddocregion class-skeleton
  title = 'Authors Style Guide Sample';
  heroes = HEROES;
  selectedHero: Hero;

  onSelect(hero: Hero): void {
    this.selectedHero = hero;
  }
// #docregion class-skeleton
}
// #enddocregion class, class-skeleton

Here's are the two corresponding code snippets displayed side-by-side.

export class AppComponent {
  title = 'Authors Style Guide Sample';
  heroes = HEROES;
  selectedHero: Hero;

  onSelect(hero: Hero): void {
    this.selectedHero = hero;
  }
}

export class AppComponent {
}

Some observations:

• The #docplaster at the top is another bit of code snippet markup. It tells the processor how to join the fragments into a single snippet.

  In this example, we tell the processor to put the fragments together without anything in between - without any "plaster". Most sample files define this empty plaster.

  If we neglected to add, #docplaster, the processor would insert the default plaster - an ellipsis comment - between the fragments. Try removing the #docplaster comment yourself to see the effect.

• One #docregion comment mentions two region names as does an #enddocregion comment. This is a convenient way to start (or stop) multiple regions on the same code line. You could have put these comments on separate lines and many authors prefer to do so.

JSON files

Code snippet markup is not supported for JSON files because comments are forbidden in JSON files.

You can display an entire JSON file by referring to it in the src attribute. But you can't display JSON fragments because you can't add #docregion tags to the file.

If the JSON file is too big, you could copy the nodes-of-interest into markdown backticks.

Unfortunately, it's easy to mistakenly create invalid JSON that way. The preferred way is to create a JSON partial file with the fragment you want to display.

You can't test this partial file and you'll never use it in the application. But at least your IDE can confirm that it is syntactically correct.

Here's an example that excerpts certain scripts from package.json into a partial file named package.1.json.

{
  "scripts": {
    "start": "concurrently \"npm run build:watch\" \"npm run serve\"",
    "test": "concurrently \"npm run build:watch\" \"karma start karma.conf.js\"",
    "lint": "tslint ./src/**/*.ts -t verbose"
  }
}

<code-example
  path="docs-style-guide/package.1.json"
  title="package.json (selected scripts)"></code-example>

Partial file naming

Many guides tell a story. In that story, the app evolves incrementally, often with simplistic or incomplete code along the way.

To tell that story in code, you'll often need to create partial files or intermediate versions of the final source code file with fragments of code that don't appear in the final app.

Such partial and intermediate files need their own names. Follow the doc sample naming convention. Add a number before the file extension as illustrated here:

package.1.json
app.component.1.ts
app.component.2.ts

You'll find many such files among the samples in the Angular documentation.

Remember to exclude these files from stackblitz by listing them in the stackblitz.json as illustrated here.

{
  "description": "Authors style guide",
  "files": [
    "!**/*.d.ts",
    "!**/*.js",
    "!**/*.[1,2,3].*"
  ],
  "tags": ["author", "style guide"]
}

Live examples

By adding <live-example> to the page you generate links that run sample code in the Stackblitz live coding environment and download that code to the reader's file system.

Live examples (AKA "stackblitz") are defined by one or more stackblitz.json files in the root of a code sample folder. Each sample folder usually has a single unnamed definition file, the default stackblitz.json.

You can create additional, named definition files in the form name.stackblitz.json. See content/examples/testing for examples.

The schema for a stackblitz.json hasn't been documented yet but looking at the stackblitz.json files in the example folders should tell you most of what you need to know.

Adding <live-example></live-example> to the page generates the two default links.

live example

1. a link to the Stackblitz defined by the default stackblitz.json file located in the code sample folder with the same name as the guide page.

2. a link that downloads that sample.

Clicking the first link opens the code sample on StackBlitz in a new browser tab.

You can change the appearance and behavior of the live example with attributes and classes.

Custom label and tooltip

Give the live example anchor a custom label and tooltip by setting the title attribute.

<live-example title="Live Example with title"></live-example>

You can achieve the same effect by putting the label between the <live-example> tags:

Live example with content label

<live-example>Live example with content label</live-example>

Live example from another guide

To link to a Stackblitz in a folder whose name is not the same as the current guide page, set the name attribute to the name of that folder.

Live Example from the Router guide

<live-example name="router">Live Example from the Router guide</live-example>

Live Example for named Stackblitz

To link to a Stackblitz defined by a named stackblitz.json file, set the stackblitz attribute. The following example links to the Stackblitz defined by second.stackblitz.json in the current guide's directory.

<live-example stackblitz="second"></live-example>

Live Example without download

To skip the download link, add the noDownload attribute.

Just the Stackblitz

<live-example noDownload>Just the Stackblitz</live-example>

Live Example with download-only

To skip the live Stackblitz link and only link to the download, add the downloadOnly attribute.

Download only

<live-example downloadOnly>Download only</live-example>

Embedded live example

By default, a live example link opens a Stackblitz in a separate browser tab. You can embed the Stackblitz within the guide page itself by adding the embedded attribute.

For performance reasons, the Stackblitz does not start right away. The reader sees an image instead. Clicking the image starts the sometimes-slow process of launching the embedded Stackblitz within an iframe on the page.

Here's an embedded live example for this guide.

<live-example embedded></live-example>

Anchors

Every section header tag is also an anchor point. Another guide page could add a link to this section by writing:

See the "Anchors" section for details.

<div class="alert is-helpful">

See the ["Anchors"](guide/docs-style-guide#anchors "Style Guide - Anchors") section for details.

</div>

When navigating within the page, you can omit the page URL when specifying the link that scrolls up to the beginning of this section.

... the link that [scrolls up](#anchors "Anchors") to ...

Ugly, long section header anchors

It is often a good idea to lock-in a good anchor name.

Sometimes the section header text makes for an unattractive anchor. This one is pretty bad.

[This one](#ugly-long-section-header-anchors) is pretty bad.

The greater danger is that a future rewording of the header text would break a link to this section.

For these reasons, it is often wise to add a custom anchor explicitly, just above the heading or text to which it applies, using the special syntax like this.

{@a ugly-anchors}

  #### Ugly, long section header anchors

Now link to that custom anchor name as you did before.

Now [link to that custom anchor name](#ugly-anchors) as you did before.

Alternatively, you can use the HTML <a> tag.

If you do, be sure to set the id attribute - not the name attribute! The docs generator will not convert the name to the proper link URL.

<a id="anchors"></a>

## Anchors

Alerts and Calllouts

Alerts and callouts present warnings, extra detail or references to other pages. They can also be used to provide commentary that enriches the reader's understanding of the content being presented.

An alert or callout must not contain anything essential to that understanding. Don't put a critical instruction or a tutorial step in a subsection.

Alerts

Alerts draw attention to short important points. Alerts should not be used for multi-line content (use callouts instead).

You'll learn about styles for live examples in the section below.

Note that at least one blank line must follow both the opening and closing <div> tags. A blank line before the closing </div> is customary but not required.

<div class="alert is-helpful">

You'll learn about styles for live examples in the [section below](guide/docs-style-guide#live-examples "Live examples").

</div>

There are three different urgency levels used to style the alerts based on the severity or importance of the content.

A critical alert.

An important alert.

A helpful, informational alert.

Here is the markup for these alerts.

<div class="alert is-critical">

A critical alert.

</div>

<div class="alert is-important">

An important alert.

</div>

<div class="alert is-helpful">

A helpful, informational alert.

</div>

Callouts

Callouts, like alerts, are meant to draw attention to important points. Use a callout when you want a riveting header and multi-line content.

If you have more than two paragraphs, consider creating a new page or making it part of the main content.

Callouts use the same urgency levels that alerts do.

Here is the markup for the first of these callouts.

<div class="callout is-critical">
<header>A critical point</header>

**Pitchfork hoodie semiotics**, roof party pop-up _paleo_ messenger bag cred Carles tousled Truffaut yr. Semiotics viral freegan VHS, Shoreditch disrupt McSweeney's. Intelligentsia kale chips Vice four dollar toast, Schlitz crucifix

</div>

Notice that:

• the callout header text is forced to all upper case
• the callout body can be written in markdown
• a blank line separates the </header> tag from the markdown content

Callouts are meant to grab the user's attention. They are not for casual asides. Please use them sparingly.

Trees

Trees can represent hierarchical data.

sample-dir
  src
    app
      app.component.ts
      app.module.ts
    styles.css
    tsconfig.json
  node_modules ...
  package.json

Here is the markup for this file tree.

<div class='filetree'>
    <div class='file'>
        sample-dir
    </div>
    <div class='children'>
        <div class='file'>
          src
        </div>
        <div class='children'>
            <div class='file'>
              app
            </div>
            <div class='children'>
                <div class='file'>
                  app.component.ts
                </div>
                <div class='file'>
                  app.module.ts
                </div>
            </div>
            <div class='file'>
              styles.css
            </div>
            <div class='file'>
              tsconfig.json
            </div>
        </div>
        <div class='file'>
          node_modules ...
        </div>
        <div class='file'>
          package.json
        </div>
    </div>
</div>

Tables

Use HTML tables to present tabular data.

Here is the markup for this table.

<style>
  td, th {vertical-align: top}
</style>

<table>
  <tr>
    <th>Framework</th>
    <th>Task</th>
    <th>Speed</th>
  </tr>
  <tr>
    <td><code>AngularJS</code></td>
    <td>Routing</td>
    <td>Fast</td>
  </tr>
  <tr>
    <td><code>Angular v2</code></td>
    <td>Routing</td>
    <!-- can use markdown too; remember blank lines -->
    <td>

      *Faster*

    </td>
  </tr>
  <tr>
    <td><code>Angular v4</code></td>
    <td>Routing</td>
    <td>

      **Fastest :)**

    </td>
  </tr>
</table>

Images

Image location

Store images in the content/images directory in a folder with the same URL as the guide page. Images for this "Authors Style Guide" page belong in the content/images/guide/docs-style-guide folder.

Angular doc generation copies these image folders to the runtime location, generated/images. Set the image src attribute to begin in that directory.

Here's the src attribute for the "flying hero" image belonging to this page.

src="generated/images/guide/docs-style-guide/flying-hero.png"

Use the HTML <img> tag

Do not use the markdown image syntax, .

Images should be specified in an <img> tag.

For accessibility, always set the alt attribute with a meaningful description of the image.

You should nest the <img> tag within a <figure> tag, which styles the image within a drop-shadow frame. You'll need the editor's permission to skip the <figure> tag.

Here's a conforming example

<figure>
  <img src="generated/images/guide/docs-style-guide/flying-hero.png"
       alt="flying hero">
</figure>

Note that the HTML image element does not have a closing tag.

Image dimensions

The doc generator reads the image dimensions from the file and adds width and height attributes to the img tag automatically. If you want to control the size of the image, supply your own width and height attributes.

Here's the "flying hero" at a more reasonable scale.

<figure>
 <img src="generated/images/guide/docs-style-guide/flying-hero.png"
   alt="flying Angular hero"
   width="200">
</figure>

Wide images can be a problem. Most browsers try to rescale the image but wide images may overflow the document in certain viewports.

Do not set a width greater than 700px. If you wish to display a larger image, provide a link to the actual image that the user can click on to see the full size image separately as in this example of source-map-explorer output from the "Ahead-of-time Compilation" guide:

Image compression

Large image files can be slow to load, harming the user experience. Always compress the image. Consider using an image compression web site such as tinypng.

Floating images

You can float the image to the left or right of text by applying the class="left" or class="right" attributes respectively.

This text wraps around to the right of the floating "flying hero" image.

Headings and code-examples automatically clear a floating image. If you need to force a piece of text to clear a floating image, add <br class="clear"> where the text should break.

The markup for the above example is:

<img src="generated/images/guide/docs-style-guide/flying-hero.png"
   alt="flying Angular hero"
   width="200"
   class="left">

This text wraps around to the right of the floating "flying hero" image.

Headings and code-examples automatically clear a floating image. If you need to force a piece of text to clear a floating image, add `<br class="clear">` where the text should break.

<br class="clear">

Note that you generally don't wrap a floating image in a <figure> element.

Floating within a subsection

If you have a floating image inside an alert, callout, or a subsection, it is a good idea to apply the clear-fix class to the div to ensure that the image doesn't overflow its container. For example:

A subsection with markdown formatted text.

<div class="alert is-helpful clear-fix">

  <img src="generated/images/guide/docs-style-guide/flying-hero.png"
    alt="flying Angular hero"
    width="100"
    class="right">

  A subsection with **markdown** formatted text.

</div>