Detailed explanation of javascript array

If you are an experienced developer, you may think that this question is simple, but sometimes we will find this question more interesting.

First, let’s take a look at the definition of the array:“An array is just a list of values which can be accessed by using an integer as the “key”. The list starts at 0 and goes up from there.”, Let's use objects to describe the definition of an array:

Copy the codeThe code is as follows:

var arr = ["benjamin", "zuojj"];

//=>

var arr = {

    "0": "benjamin",

    "1": "zuojj"

};

Looking at the example above, I always feel that something is missing, OK, the length of the array:

Copy the codeThe code is as follows:

 var arr = {

    "0"      : "benjamin",

    "1"      : "zuojj",

    "length" : 2

};

We know that in the Javascript language, an array is a special object. We can access the object's properties by accessing the array. At the same time, an array can also add properties like an object. See the following example:

Copy the codeThe code is as follows:

var arr = {
    "0"      : "benjamin",
    "1"      : "zuojj",
    "length" : 2
};
//Outputs: "benjamin"
(arr[0]);
//Outputs: 2
();

var arr = ["benjamin", "zuojj"];
= "";
//Outputs: ""
();
//Outputs: 2
();

Let’s take a look at the array methods. There are many operational methods for arrays, such as indexOf/slice/splice/sort, etc. We know that these methods actually exist in them. See the following example:

Copy the codeThe code is as follows:

var arr = ["benjamin", "zuojj"];

//Outputs: 1

(("zuojj"));

 = function(str) {

    return "It is customed indexOf!";

}

//Outputs: "It is customed indexOf!"

(("zuojj"));

In fact, we can overload all array methods using objects. See the following example of push method:

Copy the codeThe code is as follows:

var arr = {

    length: 0,

    push: function(val) {
//Assignment

        this[] = val;
//Update the array length

         += 1;
//Return the array length

        return ;

    }

}

("zuojj");

("benjamin");

//Object {0: "zuojj", 1: "benjamin", length: 2, push: function}

(arr);

But there is a literal definition of an array that cannot be implemented again:

Copy the codeThe code is as follows:

var arr = ["benjamin", "zuojj"];

But we can use constructor instead:

Copy the codeThe code is as follows:

var arr = new Array("benjamin", "zuojj");

If the literal definition array is not applicable, then we can redefine the definition of the array, in our own way.

Copy the codeThe code is as follows:

var myArr = new CustomArray("benjamin", "zuojj");

Now you know how arrays work in javascript, I hope it will be helpful to everyone.