Array.every()
.every()
The every()
method return true/false based on whether or not every element in the source array passes a certain condition or not
You’ll exit on the first failure. If the condition returns false for something, it stop processing the array there and returns.
Examples
// EXAMPLE 1
const items = [ 1, 2, 3, 4, 5, 6, 7, 8, 9 ]
const result = items.every(x => x < 10) // check every item is <10?
const result2 = items.every(x => x > 5) // check every item is >5?
console.info('result:', result) // result: true
console.info('result2:', result2) // result2: false
Check if an array contains only strings
// EXAMPLE 2
const items2 = [1, 4, 7, 'hello', 'blah']
const strings = items2.every(x => typeof x === 'string') // check if every items is a string?
console.info('strings:', strings) // strings: false
Check if a form submission was valid
// EXAMPLE 3
const fields = [
{
field: 'email',
value: 'shane@email.com',
errors: []
},
{
field: 'name',
value: '',
errors: ['No name provided']
}
]
const isValid = fields.every(x => x.errors.length === 0 ) // check if no errors?
console.info('isValid:', isValid) // isValid: false
Check if a user has finished watching the course
// EXAMPLE 4
const videos = [
{
title: 'Array methods in depth: concat',
length: 310, // video length in secs
viewed: 310 // amount of secs watched
},
{
title: 'Array methods in depth: join',
length: 420,
viewed: 360
}
]
const isComplete = videos.every(x => x.viewed === x.length)
console.info('isComplete:', isComplete) // isComplete: false