JAVASCRIPT

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

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]

javascript concat

const array1 = [1, 2, 3, 4, 5];
const array2 = [6, 7, 8, 9, 10];
const array3 = [11, 12, 13, 14, 15];

const mergeArray = array1.concat(array2, array3);

console.log(mergeArray);

how to concatenate in javscript

var one = 'Hello';
var two = 'World';

console.log(one + two);
It will print: HelloWorld

console.log(one + ' ' + two);
It will print: Hello World

js concat

let a = "foo";
let b = ["f", "o", "o"];

let c = a.concat("bar");           // "foobar"
let d = b.concat(["b", "a", "r"]); // ["f","o","o","b","a","r"]

javascript concat

const num1 = [2, 4, 5, 3, 8, 9, 11, 33, 44];
const num2 = [22, 33, 44, 55, 66, 77, 88];

const concatNumbers = num1.concat(num2)
console.log(concatNumbers)
//Expected output:
/*[
2, 4, 5, 3, 8, 9,
    11, 33, 44, 22, 33, 44,
    55, 66, 77, 88
 ]
*/

concat js

const array1 = ['a', 'b', 'c'];
const array2 = ['d', 'e', 'f'];
const array3 = array1.concat(array2);

console.log(array3);
// expected output: Array ["a", "b", "c", "d", "e", "f"]

javascript concatenation

// the fastest way to string concat in cycle when number of string is less than 1e6
// see https://medium.com/@devchache/the-performance-of-javascript-string-concat-e52466ca2b3a
// see https://www.javaer101.com/en/article/2631962.html
function concat(arr) {
    let str = '';
    for (let i = 0; i < arr.length; i++) {
        str += arr[i];
    }

    return str;
}

js concat

//ES6 spread operator same as arr1.concat(arr2)
var arr1 = ['1', '2', '3']
var arr2 = [4, 5, 6]
arr1 = [...arr1, arr2]   //... removes the [ and ] 
// leavin only an instance of inside.

output:
['1', '2', '3', 4, 5, 6 ]

string concat in js

let string1 = "Hello"
let string2 = "World"

let finalString = string1 + ", " + string2 + "!" // Hello, World!