what does concat do in javascript code example

Example 1: combine two arrays javascript

let arr1 = [0, 1, 2];
let arr2 = [3, 5, 7];
let primes = arr1.concat(arr2);

// > [0, 1, 2, 3, 5, 7]

Example 2: join 2 array in javascript

var array1 = ["Vijendra", "Singh"];
var array2 = ["Singh", "Shakya"];

console.log(array1.concat(array2));

Example 3: string concat javascript

//This method adds two or more strings and returns a new single string.

let str1 = new String( "This is string one" ); 
let str2 = new String( "This is string two" ); 
let str3 = str1.concat(str2.toString());
console.log("str1 + str2 : "+str3)

output:
str1 + str2 : This is string oneThis is string two

Example 4: javascript concat

let chocholates = ['Mars', 'BarOne', 'Tex'];
let chips = ['Doritos', 'Lays', 'Simba'];
let sweets = ['JellyTots'];

let snacks = [];
snacks.concat(chocholates);
// snacks will now be ['Mars', 'BarOne', 'Tex']
// Similarly if we left the snacks array empty and used the following
snacks.concat(chocolates, chips, sweets);
//This would return the snacks array with all other arrays combined together
// ['Mars', 'BarOne', 'Tex', 'Doritos', 'Lays', 'Simba', 'JellyTots']

Example 5: concat no and string in javascript

['Hello', ' ', 'World'].join(''); // 'Hello World'

Example 6: how the concat function works javascript

var arr = [1, 2, 3, 4];
var arr2 = [5, 6, 7, 8];

const both = arr.concat(arr2);

console.log(both);
//[1, 2, 3, 4, 5, 6, 7, 8]