JavaScript数据类型判断方法封装

var tool = {
	
	/**
	 * 判断是否为Object
	 * @param arg
	 * @returns {boolean}
	 */
	isJson: function(arg){
		if(typeof(arg) == "object" && Object.prototype.toString.call(arg).toLowerCase() == "[object object]" && !arg.length){
			return true;
		}
		return false;
	},

	/**
	 * 判断是否为Array
	 * @param array
	 * @returns {boolean}
	 */
	isArray: function(array){
		var is = ( Object.prototype.toString.call(array) === '[object Array]' );
		return is;
	},

	/**
	 * 判断是否为String
	 * @param arg
	 * @returns {boolean}
	 */
	isString: function(arg){
		if((typeof arg=='string') && arg.constructor==String){
			return true;
		}
		return false;
	},

	/**
	 * 判断是否为Function
	 * @param name
	 * @returns {boolean}
	 */
	isFunction: function(name){
		if(typeof name === "function") {
			return true;
		}
		return false;
	},

	/**
	 * 判断是否为Undefined
	 * @param arg
	 * @returns {boolean}
	 */
	isUndefined: function(arg){
		if (typeof(arg) == "undefined"){
			return true;
		}
		return false;
	},

	/**
	 * 判断是否为NULL
	 * @param arg
	 * @returns {boolean}
	 */
	isNull: function(arg){
		if(!arg && arg !== 0 && typeof arg !== "boolean"){
			return true;
		}
		return false;
	}
	
};