Remove all items after an index

Use Array.length to set a new size for an array, which is faster than Array.splice to mutate:

var array = ['mario','luigi','kong', 1, 3, 6, 8];
array.length=2;
alert(array); // shows "mario,luigi";

Why is it faster? Because .splice has to create a new array containing all the removed items, whereas .length creates nothing and “returns” a number instead of a new array.

To address .splice usage, you can feed it a negative index, along with a huge number to chop off the end of an array:

var array = ['mario','luigi','kong'];
array.splice(-1, 9e9); 
alert(array); // shows "mario,luigi";