javascript - 功能#应用垫片

Question

我正在构建一组 JavaScript 原生函数补丁，并且我有点坚持使用Function.prototype.apply旧 ies (<= v5) 的填充方法。我使用这段代码来支持.apply方法，但我不完全确定它是否是“可行的”解决方案。欢迎提供一些反馈，谢谢。这是代码：

//
(function (pFunction, str, eval) {

    // (string) Function Class: '[object Function]'
    var funcstring = str.call(pFunction);

    var isfunc = function (node) {
        return funcstring === str.call(node);
    };

    // placeholder for private `.apply()` version
    var _apply;

    if (
        // have `.apply()`?
        !isfunc(pFunction.apply)
    ) {

        _apply = function (self, arr) {

            var func;

            //`this` should be a Function{}
            if (!isfunc(func = this)) 
              throw TypeError('Function.prototype.apply called on incompatible ' + func);

          // wrap primitives
          var wrapper = Object(arr);

          // throw for primitive argument, 
          // null/undefined are accepted by native `.apply()`
          if (!(
            (wrapper === arr) || (null == arr)
          )) throw TypeError('second argument to Function.prototype.apply must be an array');

          // build a string of `arr` argument
          // that can be passed to `.eval()`
          for (
            var 
              it = -1, len = wrapper.length, args = [];

            ++it < len; 

            args.push('arr['+ it +']')
          );

          var code = args.length ?
            'func.call(self,' + args.join(',') + ');':
            'func.call(self);';

          return eval(code);
        };

        pFunction.apply = function apply (self, arr) {
            return _apply.call(this, self, arr);
        };
    }

})(
  Function.prototype, 
  Object.prototype.toString, 
  eval
);

//eof