how to insert an item into an array in js code example

Example 1: javascript insert item into array

var colors=["red","blue"];
var index=1;

//insert "white" at index 1
colors.splice(index, 0, "white");   //colors =  ["red", "white", "blue"]

Example 2: js add array items to array

var arrayA = [1, 2];
var arrayB = [3, 4];
var newArray = arrayA.concat(arrayB);