js associative array indexed by object_javascript skills

Regarding JSON objects, you can refer to wikipedia (http://zh.wikipedia.org/zh-cn/JSON) and the official website (http://www.json.org/ json-zh.html).

We often say that JavaScript natively supports json, because we can think of json as a flexible application of JavaScript’s Object object.

Usually we use json, which is mainly used as the format for front-end and back-end data exchange:

In code logic, associative arrays are more commonly used. But even then we rarely use object types as the keys of key-value pairs.

　var a= {}, b= [];

　a[b] = new Date(); //The time value can be obtained through a[b].

　The type of key name can be object, what a wonderful thing!

But there is a problem. If you want to use it this way, there is a condition: the data must be added dynamically. (Currently, I am with my classmates and have no conditions to test other browsers. Currently, I have tested IE8 and the IE kernel and weikit kernel of Sogou browser)

The test code is as follows:

Copy code The code is as follows:

var d = document. getElementById("hello"), obj = [1,2,3], a = {obj:"test"};
a[d] = "DOMElement";
alert(a[obj]); //undefined
alert(a[d]); //DOMElement
alert(a[document.getElementById("hello")]); //DOMElement
a[obj] = "Array Object" ;
alert(a[obj]); //Array Object

In fact, the key names are all strings:

Copy code The code is as follows:

var d = document.getElementById("hello"), obj = [1,2,3], a = {obj :"test"};
alert(a["obj"]); //test

var str = new String("1,2,3");
a[obj] = "Array Object";
alert(a[obj]); //Array Object
alert(a[str]); //Array Object

var Class1 = function(_val){
var val = _val;
this.toString = function(){
return val;
}
}

var obj2 = new Class1("1,2, 3");
alert(a[obj2]);//Array Object