zoukankan html css js c++ java

写自己的js的Map类

众所周之，js是没有Map类的，要想用还得自己封装一个。

(function(win) {
    var Map = function() {
        this.count = 0;
        this.entrySet = {};
    };

    var proto = Map.prototype;

    proto.size = function() {
        return this.count;
    };

    proto.isEmpty = function() {
        return this.count === 0;
    };

    proto.containsKey = function(key) {
        if (this.isEmpty()) {
            return false;
        }

        for ( var prop in this.entrySet) {
            if (prop === key) {
                return true;
            }
        }

        return false;
    };

    proto.containsValue = function(value) {
        if (this.isEmpty()) {
            return false;
        }

        for ( var key in this.entrySet) {
            if (this.entrySet[key] === value) {
                return true;
            }
        }

        return false;
    };

    proto.get = function(key) {
        if (this.isEmpty()) {
            return null;
        }

        if (this.containsKey(key)) {
            return this.entrySet[key];
        }

        return null;
    };

    proto.put = function(key, value) {
        this.entrySet[key] = value;
        this.count++;
    };

    proto.remove = function(key) {
        if (this.containsKey(key)) {
            delete this.entrySet[key];
            this.count--;
        }
    };

    proto.putAll = function(map) {
　　　　　if(!map instanceof Map){
　　　　　　  return;
　　　　　}

        for ( var key in map.entrySet) {
            this.put(key, map.entrySet[key]);
        }
    };

    proto.clear = function() {
        for ( var key in this.entrySet) {
            this.remove(key);
        }
    };

    proto.values = function() {
        var result = [];

        for ( var key in this.entrySet) {
            result.push(this.entrySet[key]);
        }

        return result;
    };

    proto.keySet = function() {
        var result = [];

        for ( var key in this.entrySet) {
            result.push(key);
        }

        return result;
    };

    proto.toString = function() {
        var result = [];
        for ( var key in this.entrySet) {
            result.push(key + ":" + this.entrySet[key]);
        }

        return "{" + result.join() + "}";
    };

    proto.valueOf = function() {
        return this.toString();
    };

    win.Map = Map;
})(window);

我们写一个页面测试一下

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<title>Insert title here</title>
<script type="text/javascript" src="Map.js"></script>
<script type="text/javascript">
window.onload = function()
{
    var map = new Map();
    map.put("name", "jack");
    map.put("age", "28");
    map.put("gender", "male");
    
    println(map.get("name"));    
    
    println(map.isEmpty());
    
    println(map.get("name"));
    
    println(map.size());
    
    println(map.keySet());
    
    println(map.values());
    
    println(map.count);
    
    println(map);
    
    println("-----------------------------------------");
    
    var map2 = new Map();
    map2.putAll(map);
    
    println(map2);
    
    map2.remove("gender");
    
    println(map2);
    println(map2.size());
    
    println(map2.containsKey("name"));
    println(map2.containsValue("jack"));
    
    map2.clear();
    
    println(map2);
    println(map2.size());
    
    println(map2.containsKey("name"));
    println(map2.containsValue("jack"));
}
</script>
</head>
<body>

</body>
</html>

输出结果如下：

jack
false
jack
3
[name,age,gender]
[jack,28,male]
3
{name:jack,age:28,gender:male}
-----------------------------------------
{name:jack,age:28,gender:male}
{name:jack,age:28}
2
true
true
{}
0
false
false

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原文地址：https://www.cnblogs.com/zfc2201/p/2594389.html