The concat() method is used to join two or more arrays together. It creates a new array that contains all the combined elements.

• Combines multiple arrays into one new array.
• Does not change the original arrays.
• Useful for merging arrays safely.

let arr1 = ["Apple", "Banana"];
let arr2 = ["Mango", "Orange"];

let result = arr1.concat(arr2);

console.log(result);

Syntax:

let newArray1 = oldArray.concat()
let newArray2 = oldArray.concat(value0)
let newArray3 = oldArray.concat(value0,value1)
.......
.......
let newArray = oldArray.concat(value1 , [ value2, [ ...,[ valueN]]])

Parameters:

The concat() method accepts multiple values or arrays as parameters. These parameters decide what will be added to the original array.

• You can pass arrays or individual values as arguments.
• Any number of arguments can be provided.
• All given values are merged into a new array.

Return value:

The concat() method returns a combined result of all the provided arrays. It produces a new array after merging everything together.

• Returns a newly created array.
• The array contains all elements from the given arguments.
• Original arrays remain unchanged.

[Example 1]: Below the Array concat() method to join three arrays.

// JavaScript code for concat() method
function func() {
    let num1 = [11, 12, 13],
        num2 = [14, 15, 16],
        num3 = [17, 18, 19];
    console.log(num1.concat(num2, num3));
}
func();

[Example 2]: The method concat() concatenates all the arguments passed to the method with the given array into one array which it returns as the answer.

// JavaScript code for concat() method
function func() {
    let alpha = ["a", "b", "c"];
    console.log(alpha.concat(1, [2, 3]));
}
func();

[Example 3]: The method concat() concatenates both arrays into one array which it returns as the answer.

// JavaScript code for concat() method
function func() {
    let num1 = [[23]];
    let num2 = [89, [67]];
    console.log(num1.concat(num2));
}
func();