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 _.flatMapDeep() method creates a flattened array of values by running each element in the given collection through the iteratee function and recursively flattens the mapped results. It is similar to _.flatMap() method.
Syntax:
_.flatMapDeep( collection, iteratee )
Parameters: This method accepts two parameters as mentioned above and described below:
- collection: It is the collection to iterate over.
- iteratee: It is the function that is invoked per iteration.
Return Value: This method returns the new flattened array.
Example 1:
// Requiring the lodash library const _ = require("lodash");       // Original array var users = (['aaa', 'bbb', 'ccc',               'ddd', 'eee', 'fff']);   // Using the _.flatMapDeep() method let flat_map =   _.flatMapDeep(users,     function duplicate(n) {       return [[[n, n]]];   } )   // Printing the output console.log(flat_map); |
Output:
[ 'aaa', 'aaa', 'bbb', 'bbb', 'ccc', 'ccc', 'ddd', 'ddd', 'eee', 'eee' ]
Example 2:
// Requiring the lodash library const _ = require("lodash");       // Original array var user1 = ([1, 2, 3, 4, 5, 6, 7]); var user2 = (['a', 'b', 'c', 'd', 'e']);   // Using the _.flatMapDeep() method let flat_map1 =   _.flatMapDeep(user1,     function makePattern(n) {       return [[[n, n + "->"]]];   } )    let flat_map2 =   _.flatMapDeep(user2,     function makePattern(n) {       return [[["<-" + n, n]]];   } )   // Printing the output console.log(flat_map1); console.log(flat_map2); |
Output:
[ 1, 1->, 2, 2->, 3, 3->, 4, 4->, 5, 5->, 6, 6->, 7, 7-> ] [ '<-a', 'a', <-'b', 'b', '<-c', 'c', '<-d', 'd', '<-e', 'e' ]
