JS - Array - push ===unshift or pop === shift

push the value to end of an array element, unshift push the element at beging of array
pop remove the last element of an array, shift remove the first element of an array. 

<script type="text/javascript">

var myArr = [2,3];
document.write("Orginal Arr "+myArr+"<br>")
myArr.push(4);
myArr.unshift(1)
document.write("unshift 1 and push 4 "+myArr+"<br>")

myArr.pop();
myArr.shift();
document.write("shift and pop "+ myArr+"<br>")

document.write(myArr.length)
</script>