I'll be going over the length/size property and a couple methods involving removing/adding an index/indexes to an array.
This leads me to the first few methods I am going to discuss. Those being .push(), .pop(), .shift(), and .unshift(). First we will touch on .push() and .unshift() as they both add an item to an array.
The difference between .push() and .unshift() is rather small. They are invoked in the same way by calling the function on an array and then passing them the value/s that you want to add to your array. The biggest difference is that .unshift() will add the value to the beginning of your array and .push() will add the value to the end of the array.
The other two methods .pop(), and .shift() are very similar to their counter parts. Rather than add values to an array they will remove items from the array. With .pop() removing the last element and .shift() removing the first element.