js常用的对象扩展方法

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/**
 * js bug：解决 javascript 的 小数截取的bug。

 * bug： alert(parseFloat(0.006).toFixed(2)); 显示 0.00 修改后显示 0.01
 */
Number.prototype.toFixed = function(d) {
	var s = this + "";
	if (!d)
		d = 0;
	if (s.indexOf(".") == -1)
		s += ".";
	s += new Array(d + 1).join("0");
	if (new RegExp("^(-|\\+)?(\\d+(\\.\\d{0," + (d + 1) + "})?)\\d*$").test(s)) {
		var s = "0" + RegExp.$2, pm = RegExp.$1, a = RegExp.$3.length, b = true;
		if (a == d + 2) {
			a = s.match(/\d/g);
			if (parseInt(a[a.length - 1]) > 4) {
				for ( var i = a.length - 2; i >= 0; i--) {
					a[i] = parseInt(a[i]) + 1;
					if (a[i] == 10) {
						a[i] = 0;
						b = i != 1;
					} else
						break;
				}
			}
			s = a.join("").replace(new RegExp("(\\d+)(\\d{" + d + "})\\d$"),
					"$1.$2");
		}
		if (b)
			s = s.substr(1);
		return (pm + s).replace(/\.$/, "");
	}
	return this + "";
};

// 给Number类型增加四则运算
/**
 * js bug：js四则运算小数精度丢失的bug修复。例如：1.5451+0.34133
 * 按理来说应该是等于1.88643,结果JS给计算时居然算成1.88629999999998了 调用方法
 */
/**
 * 加法：1.5451+0.34133 的调用方法为:var s = (1.5451).add(0.34133).toFixed(2);
 * alert((7.1).add(12.00027)+"="+(7.1+12.00027));
 */
Number.prototype.add = function(arg) {
	var bit1, bit2, m;
	try {
		bit1 = arg.toString().split(".")[1].length;
	} catch (e) {
		bit1 = 0;
	}
	try {
		bit2 = this.toString().split(".")[1].length;
	} catch (e) {
		bit2 = 0;
	}
	m = Math.pow(10, Math.max(bit1, bit2));
	return (this * m + arg * m) / m;
};
/**
 * 减法: 1.5451-0.34133 的调用方法为:var s = (1.5451).sub(0.34133);
 */
Number.prototype.sub = function(arg) {
	var bit1, bit2;
	try {
		bit1 = arg.toString().split(".")[1].length;
	} catch (e) {
		bit1 = 0;
	}
	try {
		bit2 = this.toString().split(".")[1].length;
	} catch (e) {
		bit2 = 0;
	}
	var n = Math.max(bit1, bit2);
	var m = Math.pow(10, n);
	return Number(((this * m - arg * m) / m).toFixed(n));
};
/**
 * 乘法: 1.5451*0.34133 的调用方法为:var s = (1.5451).mul(0.34133).toFixed(3);
 */
Number.prototype.mul = function(arg) {
	var bit1, bit2;
	try {
		bit1 = arg.toString().split(".")[1].length;
	} catch (e) {
		bit1 = 0;
	}
	try {
		bit2 = this.toString().split(".")[1].length;
	} catch (e) {
		bit2 = 0;
	}
	var m = bit1 + bit2;
	// var n = (bit1 > bit2) ? bit1 : bit2;
	return (Number(this.toString().replace(".", ""))
			* Number(arg.toString().replace(".", "")) / Math.pow(10, m));// .toFixed(n);
};
/**
 * 除法: 1.5451/0.34133 的调用方法为:var s = (1.5451).div(0.34133).toFixed(3);
 */
Number.prototype.div = function(arg) {
	var bit1, bit2;
	try {
		bit1 = arg.toString().split(".")[1].length;
	} catch (e) {
		bit1 = 0;
	}
	try {
		bit2 = this.toString().split(".")[1].length;
	} catch (e) {
		bit2 = 0;
	}
	var n = Math.max(bit1, bit2);
	var m = Math.pow(10, n);
	// return (Number(this.toString().replace(".", ""))*m) /
	// (Number(arg.toString().replace(".", ""))*m);
	return ((this * m) / (arg * m));
};

// 给String对象增加四则运算
/**
 * 加法：1.5451+0.34133 的调用方法为:var s = (1.5451).add(0.34133).toFixed(2);
 * alert((7.1).add(12.00027)+"="+(7.1+12.00027));
 */
String.prototype.add = function(arg) {
	return Number(this).add(arg);
};
/**
 * 减法: 1.5451-0.34133 的调用方法为:var s = (1.5451).sub(0.34133);
 */
String.prototype.sub = function(arg) {
	return Number(this).sub(arg);
};
/**
 * 乘法: 1.5451*0.34133 的调用方法为:var s = (1.5451).mul(0.34133).toFixed(3);
 */
String.prototype.mul = function(arg) {
	return Number(this).mul(arg);
};
/**
 * 除法: 1.5451/0.34133 的调用方法为:var s = (1.5451).div(0.34133).toFixed(3);
 */
String.prototype.div = function(arg) {
	return Number(this).div(arg);
};
/**
 * 处理html转义 调用方法为:var s = "aaa".escape("aaa");
 */
String.prototype.escape = function (html){
	var codeSpan = /(^|[^\\])(`+)([^\r]*?[^`])\2(?!`)/gm;
	var codeBlock = /(?:\n\n|^)((?:(?:[ ]{4}|\t).*\n+)+)(\n*[ ]{0,3}[^ \t\n]|(?=~0))/g;
	var spans = [];
	var blocks = [];
	var text = String(html).replace(/\r\n/g, '\n').replace('/\r/g', '\n');
	text = '\n\n' + text + '\n\n';
	texttext = text.replace(codeSpan, function(code){
		spans.push(code);
		return '`span`';
	});
	text += '~0';
	return text.replace(codeBlock, function(code){
		blocks.push(code);
		return '\n\tblock';
	}).replace(/&(?!\w+;)/g, '&').replace(//g, '>').replace(/"/g, '"').replace(/`span`/g, function(){
		return spans.shift();
	}).replace(/\n\tblock/g, function(){
		return blocks.shift();
	}).replace(/~0$/, '').replace(/^\n\n/, '').replace(/\n\n$/, '');
};

// 等比例缩放图片
//var flag = false;
/**
 * ImgD：原图 maxWidth：允许的最大宽度 maxHeight：允许的最大高度
 */
function resizeimg(ImgD, maxWidth, maxHeight) {
	//ImgD.style.display="none"; //隐藏加到这儿不管用，应该放到img标签中
	var image = new Image();
	var iwidth = maxWidth; // 定义允许图片宽度
	var iheight = maxHeight; // 定义允许图片高度
	image.src = ImgD.src;
	if (image.width > 0 && image.height > 0) {
		//flag = true;
		if (image.width / image.height >= iwidth / iheight) {
			if (image.width > iwidth) {
				ImgD.width = iwidth;
				ImgD.height = (image.height * iwidth) / image.width;
			} else {
				ImgD.width = image.width;
				ImgD.height = image.height;
			}
			//ImgD.alt = image.width + "×" + image.height;
		} else {
			if (image.height > iheight) {
				ImgD.height = iheight;
				ImgD.width = (image.width * iheight) / image.height;
			} else {
				ImgD.width = image.width;
				ImgD.height = image.height;
			}
			//ImgD.alt = image.width + "×" + image.height;
		}
	}
	centerImage(ImgD, maxWidth, maxHeight);
	ImgD.style.display="inline";
}
/**
 * Date：给日期对象添加格式化方法
 * 使用方法 var date = new Date().format('yyyy-MM-dd')
 */
Date.prototype.format = function(format){ 
	var o = {
		"M+" : this.getMonth()+1, //month
		"d+" : this.getDate(), //day
		"h+" : this.getHours(), //hour
		"m+" : this.getMinutes(), //minute
		"s+" : this.getSeconds(), //second
		"q+" : Math.floor((this.getMonth()+3)/3), //quarter
		"S" : this.getMilliseconds() //millisecond
	} 
	if(/(y+)/.test(format)) {
		format = format.replace(RegExp.$1, (this.getFullYear()+"").substr(4 - RegExp.$1.length));
	}
	for(var k in o) {
		if(new RegExp("("+ k +")").test(format)) {
			format = format.replace(RegExp.$1, RegExp.$1.length==1 ? o[k] : ("00"+ o[k]).substr((""+ o[k]).length)); 
		}
	}
	return format;
}

/**
 * 原网址：http://www.cnblogs.com/mingmingruyuedlut/archive/2013/05/19/3082177.html
 * 扩展 Number 对象 formatMoney()方法（参数：保留小数位数，货币符号，整数部分千位分隔符，小数分隔符）:
 * 调用方法为:var s = (60000).formatMoney(0,"","","");结果为：s = 60,000
 */
Number.prototype.formatMoney = function (places, symbol, thousand, decimal) {
    places = !isNaN(places = Math.abs(places)) ? places : 2;
    symbol = symbol !== undefined ? symbol : "$";
    thousand = thousand || ",";
    decimal = decimal || ".";
    var number = this,
        negative = number < 0 ? "-" : "",
        i = parseInt(number = Math.abs(+number || 0).toFixed(places), 10) + "",
        j = (j = i.length) > 3 ? j % 3 : 0;
    return symbol + negative + (j ? i.substr(0, j) + thousand : "") + i.substr(j).replace(/(\d{3})(?=\d)/g, "$1" + thousand) + (places ? decimal + Math.abs(number - i).toFixed(places).slice(2) : "");
};

function centerImage(imgD, maxWidth, maxHeight) {
	// var div = imgD.parentNode;// 获取包含本图片的div不用这个
	if (imgD.height < maxHeight) {
		var top = (maxHeight - imgD.height) / 2-2;
		//ie6不支持这么获取高度，所以ie6下不执行
		if(imgD.height!=0){
			imgD.style.marginTop = top + "px";
		}
	}
	if (imgD.width < maxWidth) {
		var left = (maxWidth - imgD.width) / 2;
		//ie6不支持这么获取宽度，所以ie6下不执行
		if(imgD.width!=0){
			imgD.style.marginLeft = left + "px";
		}
	}
}
/**
 * 将字符串格式的日期（如：20150415092645）转换成js Date对象
 * 注意Date对象的初始化方式
 * */
function js_patch_getdate(stime) {
	var datetime = new Date(
			parseFloat(stime.substr(0, 4)),
			parseFloat(stime.substr(4, 2) - 1),
			parseFloat(stime.substr(6, 2)),
			parseFloat(stime.substr(8, 2)),
			parseFloat(stime.substr(10, 2)),
			parseFloat(stime.substr(12, 2)));
	return datetime;
}
function js_patch_fillZero(num, digit) {
	var str = '' + num;
	while (str.length < digit) {
		str = '0' + str;
	}
	return str;
}	
function debug_showAttr(obj)
{
	var str="begin:the attribute of "+obj+"
";
	for(var i in obj)
	{
		str+=""+i+"=="+obj[i]+"
";
	}
	document.body.innerHTML+=str;
}
function debug_showMsg(str)
{
	document.body.innerHTML+=str;
}
function debug_showMsgSrc(str)
{
	document.body.innerHTML+=str.replace(//g,">");
}