append item to array javascript

1var colors=["red","white"];
2colors.push("blue");//append 'blue' to colors

1var colors=["red","blue"];
2var index=1;
3
4//insert "white" at index 1
5colors.splice(index, 0, "white");   //colors =  ["red", "white", "blue"]
6

1var colors= ["red","blue"];
2	colors.push("yellow"); 

1const array1 = ['a', 'b', 'c'];
2const array2 = ['d', 'e', 'f'];
3const array3 = array1.concat(array2);

1var array = [];
2array.push(element)
3console.log(array);

1arr.push(item);