Lodash _.every() Method

Lodash is a JavaScript library that works on the top of underscore.js. Lodash helps in working with arrays, collection, strings, objects, numbers, etc. The _.every method checks if the predicate returns true for all elements of collection and iteration is stopped once the predicate returns falsely.

Note: Also this method returns true for empty collections because everything is true for elements of empty collections.

Syntax:

_.every(collection, [predicate=_.identity])

Parameters: This method accepts two parameters as mentioned above and described below:

• collection (Array|Object): This parameter holds the collection to iterate over.
• [predicate=_.identity] (Function): This parameter holds the function invoked per iteration.

Return Value: This method is used to returns true if all elements pass the predicate check, else false.

Example 1: Here, const _ = require(‘lodash’) is used to import the lodash library in the file.

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array

var obj1 = ([true, 1, null, 'yes']);
var obj2 = ([true, 2, 'active', 'yes']);

// Use of _.every() method

let x = _.every(obj1, Boolean);
let y = _.every(obj2, Boolean);

// Printing the output
console.log(x);
console.log(y);

Output:

false
true

Example 2:

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array

var users = [ { 'user': 'jonny', 'age': 30, 'active': false },
              { 'user': 'harry', 'age': 35, 'active': false } ];

// Use of _.every() method
// The `_.matches` iteratee shorthand.

let x = _.every(users, { 'user': 'barney', 'active': false });

// Printing the output
console.log(x);

Output:

false

Example 3:

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array

var users = [
  { 'user': 'jonny', 'age': 30, 'active': false },
  { 'user': 'harry',  'age': 35, 'active': false }
];

// Use of _.every() method
// The `_.matchesProperty` iteratee shorthand.

let x = _.every(users, ['active', false]);

// Printing the output
console.log(x);

Output:

true

Example 4:

javascript

// Requiring the lodash library
const _ = require("lodash");

// Original array

var users = [
  { 'user': 'jonny', 'age': 30, 'active': false },
  { 'user': 'harry',  'age': 35, 'active': false }
];

// Use of _.every() method
// The `_.property` iteratee shorthand.

let x = _.every(users, 'active');

// Printing the output
console.log(x);

Output:

false

Note: This code will not work in normal JavaScript because it requires the library lodash to be installed.