js simulates simple functional code similar to hashtable under c#_javascript skills

If we are in C#, we can easily implement this function as long as we use hashtable or dictionary to get the value based on the key. In fact, if we deal with it a little bit, js can also implement functions similar to hashtable. Below is a summary of the implementation methods used in the author's development, focusing on pasting the code.
1. Implementation idea: The main purpose is to use the hasOwnProperty method of the prototype to determine whether the item in the object should be added, removed, or a matching item should be taken out, etc. The reason hasOwnProperty is smarter and faster than traversing array values ​​is that, at least from a code perspective, it has O(1) complexity.
2. Implementation code

Copy code The code is as follows:

// js hash Table
function HashTable() {
this.ObjArr = {};
this.Count = 0;
//Add
this.Add = function(key, value) {
if (this.ObjArr.hasOwnProperty(key)) {
return false; //If the key already exists, do not add
}
else {
this.ObjArr[key] = value;
this.Count ;
return true;
}
}
//Whether it contains an item
this.Contains = function(key) {
return this.ObjArr.hasOwnProperty (key);
}
//Getting a certain item is actually equivalent to this.ObjArr[key]
this.GetValue = function(key) {
if (this.Contains(key) ) {
return this.ObjArr[key];
}
else {
throw Error("Hashtable not contains the key: " String(key)); //Script error
/ /return;
}
}
//Remove
this.Remove = function(key) {
if (this.Contains(key)) {
delete this.ObjArr [key];
this.Count--;
}
}
//Clear
this.Clear = function() {
this.ObjArr = {}; this. Count = 0;
}
}

3. Test code
Code

Copy code The code is as follows:

//Employee
function(employeeid, userName) {
this.id = id;
this.userName = userName;
}
function test() {
var ht = new HashTable();
var tmpEmployee = null;
for (var i = 1; i < 6; i ) {
tmpEmployee = new employee(i, "Employee_" i);
ht.Add(i, tmpEmployee);
}
for (var i = 1; i <= ht.Count; i ) {
alert(ht.GetValue(i).userName); //actually equivalent to ht.ObjArr[i].userName
//alert(ht.ObjArr[i].userName);
}
ht.Remove(1);
alert(ht.Contains(1)); //false
alert(ht.Contains(2)); //true
//alert( ht.GetValue(1)); //Exception
var result = ht.GetValue(2);
if (result != null) {
alert("Employee Id:" result.id "; UserName:" result.userName);
}
ht.Add(2, "This key already exists!"); //Add is invalid
//ht.Clear(); //Clear
alert(ht.Count);
}

It is very simple to call. As long as you create a new hashtable object, common functions will be available. Isn't it very simple? Enjoy it.
Summary: The prototype chain (prototype chain) and the scope chain are the two core parts of js. By learning and understanding them, many complex problems will be easily solved; by making good use of their characteristics, we can easily implement very flexible and efficient functions.