String. Format = function (str ){
Var reg;
Var args;
// Customize an undifined to increase the speed
Var undifined;
If (arguments [1] & typeof (arguments [1]) = "object "){
Reg = new RegExp ("\\{ ([^ \ d] \\ w *) \\}", "g ");
Args = arguments [1];
}
Else {
Reg = new RegExp ("\\{ (\ d +) \\}", "g ");
// Convert arguments into an array and assign it to args
Args = Array. prototype. slice. call (arguments );
For (var I = 0; I <args. length-1; I ++)
{
Args [I] = args [I + 1];
}
// Remove the first value of args because the first value is a string that needs to be matched by regular expressions.
Args [I] = undifined;
}
Return str. replace (reg, function (){
Var val = args [arguments [1];
Return val = undifined? Arguments [0]: val;
});
};
Alert (String. Format ("{0}, {1}, {2}", "aa", "bb "))
Alert (String. Format ("{aa}, {bb}", {aa: 123, bb: 456 }))
