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Lodash _.flatMap() Method

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  • Last Updated : 10 Sep, 2020

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 _.flatMap() method creates a flattened array of values by running each element in collection through iteratee and flattening the mapped results.

Syntax:

_.flatMap(collection, iteratee)

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

  • collection: This parameter holds the collection to iterate over.
  • iteratee: This parameter holds the function invoked per iteration.

Return Value: This method returns the new flattened array.

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 user1 = ([35, 47, 58, 69, 94, 13, 72]);
  
// Use of _.flatMap() method
let gfg1 = _.flatMap(user1, function duplicate(n) {
  return [n, n];
})
  
// Printing the output 
console.log(gfg1);


Output:

[
  35, 35, 47, 47, 58, 58, 
  69, 69, 94, 94, 13, 13,
  72, 72
]

Example 2:

javascript




// Requiring the lodash library 
const _ = require("lodash"); 
      
// Original array 
var user1 = ([3.5, 4.7, 5.8, 6.9, 9.4, 1.3, 7.2]);
var user2 = ([3, 4, 5, 9, 9, 1, 7]);
  
// Use of _.flatMap() method
let gfg1 = _.flatMap(user1, function duplicate(n) {
  return [n, n];
})
  
let gfg2 = _.flatMap(user2, function duplicate(n) {
  return [n, n];
})
  
// Printing the output 
console.log(gfg1);
console.log(gfg2);


Output:

[
  3.5, 3.5, 4.7, 4.7, 5.8, 5.8, 
  6.9, 6.9, 9.4, 9.4, 1.3, 1.3,
  7.2, 7.2
]
[
  3, 3, 4, 4, 5, 5,
  9, 9, 9, 9, 1, 1,
  7, 7
]

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


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