how to add to string in js code example

Example 1: string concatenation in js

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

Example 2: how to concatenate strings and variables in javascript

const helloName = name => `Hello ${name}!`

Example 3: javascript add to string

var s = 'hell'
s = s + 'o'