js中的占位函数

String.prototype.signMix= function() {
    if(arguments.length === 0) return this;
    var param = arguments[0], str= this;
    if(typeof(param) === ‘object‘) {
        for(var key in param)
            str = str.replace(new RegExp("\\{" + key + "\\}", "g"), param[key]);
        return str;
    } else {
        for(var i = 0; i < arguments.length; i++)
            str = str.replace(new RegExp("\\{" + i + "\\}", "g"), arguments[i]);
        return str;
    }
};