js 时间格式替代多余字符代码

Date.prototype.format = function(style) {
        if(style==undefined || style==null) style="yyyy-MM-dd";
        var o = {
            "M+" : this.getMonth() + 1, //month
            "d+" : this.getDate(),      //day
            "h+" : this.getHours(),     //hour
            "m+" : this.getMinutes(),   //minute
            "s+" : this.getSeconds(),   //second
            "w+" : "天一二三四五六".charAt(this.getDay()),   //week
            "q+" : Math.floor((this.getMonth() + 3) / 3), //quarter
            "S" : this.getMilliseconds() //millisecond
        }
        if(/(y+)/.test(style)) {
            style = style.replace(RegExp.$1,
            (this.getFullYear() + "").substr(4 - RegExp.$1.length));
        }
        for(var k in o){
            if(new RegExp("("+ k +")").test(style)){
                style = style.replace(RegExp.$1,
                RegExp.$1.length == 1 ? o[k] :
                ("00" + o[k]).substr(("" + o[k]).length));
            }
        }
        return style;
};


String.prototype.createShortDisp = function(text,num){
	if(num==undefined || num==null) num=10;
 	var result=text;
 	if (text.length > num) result = text.substring(0, num) + "...";
 	return "<span title = '" + text + "'>" + result + "</>";
}