Function.prototype什么意思，Function指的是什么，不是很清楚解决方案

/**
 * @class Function
 * These functions are available on every Function object (any JavaScript function).
 */
Ext.apply(Function.prototype, {
     /**
     * Creates an interceptor function. The passed fcn is called before the original one. If it returns false,
     * the original one is not called. The resulting function returns the results of the original function.
     * The passed fcn is called with the parameters of the original function. Example usage:
     * <pre><code>
var sayHi = function(name){
    alert('Hi, ' + name);
}

sayHi('Fred'); // alerts "Hi, Fred"

// create a new function that validates input without
// directly modifying the original function:
var sayHiToFriend = sayHi.createInterceptor(function(name){
    return name == 'Brian';
});

sayHiToFriend('Fred');  // no alert
sayHiToFriend('Brian'); // alerts "Hi, Brian"
</code></pre>
     * @param {Function} fcn The function to call before the original
     * @param {Object} scope (optional) The scope of the passed fcn (Defaults to scope of original function or window)
     * @return {Function} The new function
     */
    createInterceptor : function(fcn, scope){
        var method = this;
        return !Ext.isFunction(fcn) ?
                this :
                function() {
                    var me = this,
                        args = arguments;
                    fcn.target = me;
                    fcn.method = method;
                    return (fcn.apply(scope || me || window, args) !== false) ?
                            method.apply(me || window, args) :
                            null;
                };
    },

     /**
     * Creates a callback that passes arguments[0], arguments[1], arguments[2], ...
     * Call directly on any function. Example: <code>myFunction.createCallback(arg1, arg2)</code>
     * Will create a function that is bound to those 2 args. <b>If a specific scope is required in the
     * callback, use {@link #createDelegate} instead.</b> The function returned by createCallback always
     * executes in the window scope.
     * <p>This method is required when you want to pass arguments to a callback function.  If no arguments
     * are needed, you can simply pass a reference to the function as a callback (e.g., callback: myFn).
     * However, if you tried to pass a function with arguments (e.g., callback: myFn(arg1, arg2)) the function
     * would simply execute immediately when the code is parsed. Example usage:
     * <pre><code>
var sayHi = function(name){
    alert('Hi, ' + name);
}

// clicking the button alerts "Hi, Fred"
new Ext.Button({
    text: 'Say Hi',
    renderTo: Ext.getBody(),
    handler: sayHi.createCallback('Fred')
});
</code></pre>
     * @return {Function} The new function
    */
    createCallback : function(/*args...*/){
        // make args available, in function below
        var args = arguments,
            method = this;
        return function() {
            return method.apply(window, args);
        };
    },

    /**
     * Creates a delegate (callback) that sets the scope to obj.
     * Call directly on any function. Example: <code>this.myFunction.createDelegate(this, [arg1, arg2])</code>
     * Will create a function that is automatically scoped to obj so that the <tt>this</tt> variable inside the
     * callback points to obj. Example usage:
     * <pre><code>
var sayHi = function(name){
    // Note this use of "this.text" here.  This function expects to
    // execute within a scope that contains a text property.  In this
    // example, the "this" variable is pointing to the btn object that
    // was passed in createDelegate below.
    alert('Hi, ' + name + '. You clicked the "' + this.text + '" button.');
}

var btn = new Ext.Button({
    text: 'Say Hi',
    renderTo: Ext.getBody()
});

// This callback will execute in the scope of the
// button instance. Clicking the button alerts
// "Hi, Fred. You clicked the "Say Hi" button."
btn.on('click', sayHi.createDelegate(btn, ['Fred']));
</code></pre>
     * @param {Object} obj (optional) The object for which the scope is set
     * @param {Array} args (optional) Overrides arguments for the call. (Defaults to the arguments passed by the caller)
     * @param {Boolean/Number} appendArgs (optional) if True args are appended to call args instead of overriding,
     *                                             if a number the args are inserted at the specified position
     * @return {Function} The new function
     */
    createDelegate : function(obj, args, appendArgs){
        var method = this;
        return function() {
            var callArgs = args || arguments;
            if (appendArgs === true){
                callArgs = Array.prototype.slice.call(arguments, 0);
                callArgs = callArgs.concat(args);
            }else if (typeof appendArgs == "number"){
                callArgs = Array.prototype.slice.call(arguments, 0); // copy arguments first
                var applyArgs = [appendArgs, 0].concat(args); // create method call params
                Array.prototype.splice.apply(callArgs, applyArgs); // splice them in
            }
            return method.apply(obj || window, callArgs);
        };
    },

    /**
     * Calls this function after the number of millseconds specified, optionally in a specific scope. Example usage:
     * <pre><code>
var sayHi = function(name){
    alert('Hi, ' + name);
}

// executes immediately:
sayHi('Fred');

// executes after 2 seconds:
sayHi.defer(2000, this, ['Fred']);

// this syntax is sometimes useful for deferring
// execution of an anonymous function:
(function(){
    alert('Anonymous');
}).defer(100);
</code></pre>
     * @param {Number} millis The number of milliseconds for the setTimeout call (if 0 the function is executed immediately)
     * @param {Object} obj (optional) The object for which the scope is set
     * @param {Array} args (optional) Overrides arguments for the call. (Defaults to the arguments passed by the caller)
     * @param {Boolean/Number} appendArgs (optional) if True args are appended to call args instead of overriding,
     *                                             if a number the args are inserted at the specified position
     * @return {Number} The timeout id that can be used with clearTimeout
     */
    defer : function(millis, obj, args, appendArgs){
        var fn = this.createDelegate(obj, args, appendArgs);
        if(millis){
            return setTimeout(fn, millis);
        }
        fn();
        return 0;
    }
});