JS 中实现 string.Format()

String.prototype.format = function(args) {
if (arguments.length>0) {
var result = this;
if (arguments.length == 1 && typeof (args) == "object") {
for (var key in args) {
var reg=new RegExp ("({"+key+"})","g");
result = result.replace(reg, args[key]);
}
}
else {
for (var i = 0; i < arguments.length; i++) {
if(arguments[i]==undefined)
{
return "";
}
else
{
var reg=new RegExp ("({["+i+"]})","g");
result = result.replace(reg, arguments[i]);
}
}
}
return result;
}
else {
return this;
}
}

例：
//两种调用方式
var template1="我是{0}，今年{1}了";
var template2="我是{name}，今年{age}了";
var result1=template1.format("loogn",22);
var result2=template1.format({name:"loogn",age:22});
//两个结果都是"我是loogn，今年22了"
记录下来方便以后用。呵呵