JavaScript Map 实现

Posted 2020-08-03 Sallet

//定义map     
function Map() {
	this.container = {};
}
//将key-value放入map中     
Map.prototype.put = function(key, value) {
	try {
		if (key != null && key != "")
			this.container[key] = value;
	} catch (e) {
		return e;
	}
};

//根据key从map中取出对应的value     
Map.prototype.get = function(key) {
	try {
		return this.container[key];
	} catch (e) {
		return e;
	}
};

//判断map中是否包含指定的key     
Map.prototype.containsKey = function(key) {
	try {
		for ( var p in this.container) {
			if (p == key)
				return true;
		}
		return false;

	} catch (e) {
		return e;
	}

}

//判断map中是否包含指定的value     
Map.prototype.containsValue = function(value) {
	try {
		for ( var p in this.container) {
			if (this.container[p] === value)
				return true;
		}
		return false;

	} catch (e) {
		return e;
	}
};

//删除map中指定的key     
Map.prototype.remove = function(key) {
	try {
		delete this.container[key];
	} catch (e) {
		return e;
	}
};

//清空map     
Map.prototype.clear = function() {
	try {
		delete this.container;
		this.container = {};

	} catch (e) {
		return e;
	}
};

//判断map是否为空     
Map.prototype.isEmpty = function() {

	if (this.keySet().length == 0)
		return true;
	else
		return false;
};

//获取map的大小     
Map.prototype.size = function() {

	return this.keySet().length;
}

//返回map中的key值数组     
Map.prototype.keySet = function() {
	var keys = new Array();
	for ( var p in this.container) {
		keys.push(p);
	}

	return keys;
}

//返回map中的values值数组     
Map.prototype.values = function() {
	var valuesArray = new Array();
	var keys = this.keySet();
	for (var i = 0; i < keys.length; i++) {
		valuesArray.push(this.container[keys[i]]);
	}
	return valuesArray;
}

//返回 map 中的 entrySet 对象
Map.prototype.entrySet = function() {
	var array = new Array();
	var keys = this.keySet();
	for (var i = 0; i < keys.length; i++) {
		array.push(keys[i],this.container[keys[i]]);
	}
	return array;
}

//返回 map 中的 value值的和(当值是 Nunmber 类型时有效)
Map.prototype.sumValues = function() {
	var values = this.values();
	var result = 0;
	for (var i = 0; i < values.length; i++) {
		result += Number(values[i]);
	}
	return result;
}

///计算两个整数的百分比值 
function toPercent(num, total){
	num = parseFloat(num); 
	total = parseFloat(total); 
	if (isNaN(num) || isNaN(total)) { 
		return "0"; 
	} 
	return total <= 0 ? "0%" : (Math.round(num / total * 10000) / 100.00 + "%"); 
//	return (Math.round(this * 10000)/100).toFixed(2) + ‘%‘;
}