concatenate functions javascript code example

Example 1: 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 2: 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;
}