Lodash _.takeWhile() Method

Lodash _.taketWhile the method is used to create a slice of an array in which elements are taken from the beginning. Also, these elements are taken until the predicate returns falsely.

Syntax:

_.takeWhile(array, [predicate=_.identity]);

Parameters:

• array: This parameter holds the array to query.
• [predicate=_.identity]: This parameter holds the function invoked per iteration.

Return Value:

This method is used to return the slice of the array.

Example 1: In this example, it is returning the two objects of an array as the third one is returning false.

javascript

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

// Original array
let users = [
    { 'user': 'jupiter', 'active': false },
    { 'user': 'mercury', 'active': false },
    { 'user': 'saturn', 'active': true }
];


// Use of _.takeWhile()
// method
let gfg = _.takeWhile(users, function (o) { return !o.active; });

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

Output:

[{ user: 'jupiter', active: false },
 {user: 'mercury', active: false}]

Example 2: In this example, it is returning the one object of an array as the second one is returning false.

javascript

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

// Original array
let users = [
    { 'user': 'jupiter', 'active': false },
    { 'user': 'mercury', 'active': false },
    { 'user': 'saturn', 'active': true }
];

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

let gfg = _.takeWhile(users, { 'user': 'jupiter', 'active': false });

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

Output:

[{ user: 'jupiter', active: false }]

Example 3: In this example, it is returning the two objects of an array as the third one is returning false.

javascript

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

// Original array
let users = [
    { 'user': 'jupiter', 'active': false },
    { 'user': 'mercury', 'active': false },
    { 'user': 'saturn', 'active': true }
];

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

let gfg = _.takeWhile(users, ['active', false]);

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

Output:

[{ user: 'jupiter', active: false },
 {user: 'mercury', active: false}]

Example 4: In this example, it is returning empty array as first one is returning false so it will not check further.

javascript

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

// Original array
let users = [
    { 'user': 'jupiter', 'active': false },
    { 'user': 'mercury', 'active': false },
    { 'user': 'saturn', 'active': true }
];

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

let gfg = _.takeWhile(users, 'active');

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

Output:

[]

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