2 Dimensional arrays
6
In ES6, we can flatten the array by the spread operator ...:
function flattenES6(arr) {
return [].concat(...arr);
}
var arrL1 = [1, 2, [3, 4]];
console.log(flattenES6(arrL1)); // [1, 2, 3, 4]
5
In ES5, we can acheive that by .apply():
function flatten(arr) {
...
