Lodash _.cat() Method

Lodash is a JavaScript library that works on the top of underscore.js. Lodash helps in working with arrays, strings, objects, numbers, etc.

The _.cat() method is used to concatenate zero or more arguments into one array. It can be used to concatenate multiple types of arguments,

Syntax:

_.cat( arg1, arg2, ..., argn )

Parameters:

• args: This method accepts multiple arguments to concatenate into a single array.

Return Value: This method returns a concatenated array.

Note: This method will not work in normal JavaScript because it requires the Lodash contrib library to be installed. The lodash-contrib library can be installed using npm install lodash-contrib –save

Example 1: In this example, we will concatenate 2 arrays.

Javascript

// Defining lodash contrib variable
var _ = require('lodash-contrib');

// Array1
var arr1 = [1,2,3];

// Array2
var arr2 = [4,5,6];

// Concatenation
var arr = _.cat(arr1, arr2);

console.log("array 1 : " + arr1);
console.log("array 2 : " + arr2);
console.log("concatenated array : " + arr);

Output:

array 1 : 1,2,3
array 2 : 4,5,6
concatenated array : 1,2,3,4,5,6

Example 2: In this example, we will concatenate 2 numbers to form an array.

Javascript

// Defining lodash contrib variable
var _ = require('lodash-contrib');

// Number 1
var num1 = 1;

// Number 2
var num2 = 4;

// Concatenation
var arr = _.cat(num1, num2);
console.log("num1 : " + num1);
console.log("num2 : " + num2);
console.log("Concatenated array : " + arr);

Output:

num1 : 1
num2 : 4
Concatenated array : 1,4

Example 3: In this example, we will concatenate 3 arrays.

Javascript

// Defining lodash contrib variable
var _ = require('lodash-contrib');

// Array1
var arr1 = [1,2,3];

// Array2
var arr2 = [4,5,6];

// Array3
var arr3 = [7,8,9];

// Concatenation
var arr = _.cat(arr1, arr2, arr3);
console.log("array 1 : " + arr1);
console.log("array 2 : " + arr2);
console.log("array 3 : " + arr3);
console.log("Concatenated array : " + arr);

Output:

array 1 : 1,2,3
array 2 : 4,5,6
array 3 : 7,8,9
Concatenated array : 1,2,3,4,5,6,7,8,9

Example 4: The _.cat() function will also work with the arguments object as if it were an array.

Javascript

// Defining lodash contrib variable
var _ = require('lodash-contrib');

// Function
function f(){
  return _.cat(arguments, 4,5,6);
}

console.log("Array is : " + f(1,2,3));

Output:

Array is : 1,2,3,4,5,6