Summary of multiple methods for obtaining the last element of JS array

I will discuss the text with you js There are many ways to get the last element of the array .

length

Because the array index is from 0 Start , So we can access the array length minus 1, This achieves the goal of accessing the last element .

notes ： If the location of the index illegal , Then it will return to undefined.

var my_array = [1,2,3,4,5];
var last_element = my_array[my_array.length - 1]; // 5

prototype attribute

We can bind the last element of the access array to the prototype chain , This makes it easy to use for many times .

For example, the following code ：

if (!Array.prototype.last){
    Array.prototype.last = function(){
        return this[this.length - 1];
    };
};

pop Method

because pop Is used to delete the last element of the array , And it returns the deleted element , So we can use this method directly .

For example, the following code ：

var arr = [1,2,3,4,5];
var lastElement = [...arr].pop();//5

notes ：pop The method has side effects , Will change the original array .