has()

Returns true if the key is defined in the provided collection.

A functional alternative to collection.has(key) which will also work with plain Objects and Arrays as an alternative for collection.hasOwnProperty(key).

const { has } = require('immutable')
has([ 'dog', 'frog', 'cat' ], 2) // true
has([ 'dog', 'frog', 'cat' ], 5) // false
has({ x: 123, y: 456 }, 'x') // true
has({ x: 123, y: 456 }, 'z') // falserun it