JAVASCRIPT

string concatenation in js

var str1 = "Hello ";
var str2 = "world!";
var res = str1.concat(str2);
console.log(res);

what concatenation in javascript

/*
Note:

Concatenation in javascript
Concat() The concat() method is used to merge two or more arrays. 
This method does not change the existing arrays but instead returns a new array.
Concatenation is when you add string to an integer then the integer becomes a string.
*/


//CODE//

var myAge = 100;
console.log("My age is" + myAge);
myAge = 29;
console.log("My age next year will be" + myAge);

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

string javascript concatenation

    var dest = new String("");
    var src = new String("aze");
    var ar = new Array();
    ...
    ar.push(src);
    ar.push(src);
    ...
    dest = ar.join("");

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
 ]
*/

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;
}

string javascript concatenation

    var dest = new String("");
    var src = new String("aze");
    ...
    dest += src + src + src + src + src;