closures

问题 What a crappy title. Maybe someone can edit it for me. Here's the scoop: I need to work in jQuery no-conflict mode, but I'd still like to take advantage of the $ shortcut, so all of my functions etc are defined within the typical closure of (function($){ ... })(jQuery); All this is defined in an external source.js file that is included at the top of my HTML web page. A little later on, I need to add some inline <script> that uses one of the utility functions I defined within the closure.

问题 the question is pretty similar to this thread Javascript..totally lost in this tutorial. function findSequence(goal) { function find(start, history) { if (start == goal) return history; else if (start > goal) return null; else return find(start + 5, "(" + history + " + 5)") || find(start * 3, "(" + history + " * 3)"); } return find(1, "1"); } print(findSequence(24)); I got stuck at this part : find(start * 3, "(" + history + " * 3)"); each time start goes beyond goal what does it do? it says

问题 I have been reading about closures and javascript, and I thought I got it, till I tried this: var Object5 = function (param) { var x = 0; var squareBrace = function () { return '[' + param + x + ']'; }; this.toString = function () { x = x + 1; return squareBrace(); }; }; Then I ran this code: var counter = new Object5("Counter: "); print("Has x:" + ('x' in counter)); print("Has f:" + ('f' in counter)); print("Can access x:" + (!!counter.x)); print("Can Invoke f:" + (!!counter.f)); print

问题 i have this two recursive functions in javascript. first function returns digits of the input number in right to left order second function returns them in left to right order. function first(n){ if(n > 0){ m = Math.floor( n/10 ); v = ( n - m * 10 ) + " " + first(m); return v; } return ""; } function second(n){ if(n > 0){ m = Math.floor( n/10 ); v = second(m) + " " + ( n - m * 10 ); return v; } return ""; } result of the first function is 7 6 1 result of the second function is 1 16 167 but I

问题 Q: I am trying to work out why there is a delete statement in this code? My assumption is foo will be dereferenced once statement has finished executing therefore would be no need to explicitly do it. (function () { var foo = globalObject; foo.bar = function () { //code here } delete foo; }()); What is going on here? 回答1: See this article on when To and Not To use the delete operator. This does not appear to be a proper use. Local variables cannot be deleted as they are marked internally with

问题 I feel like there is something missing from it. Here it is: Nested functions and closures You can nest a function within a function. The nested (inner) function is private to its containing (outer) function. It also forms a closure. A closure is an expression (typically a function) that can have free variables together with an environment that binds those variables (that "closes" the expression). Since a nested function is a closure, this means that a nested function can "inherit" the

问题 I have the following 2 controllers listed below. I'm using delegation to try and create a progressWindow which will run code and print it nicely but where the code is arbitrary. The closures are defined by the class conforming to the protocol (in my case SyncViewController), but I want to change the UI of the progressWindowViewController from SyncViewControllers codeToRun {} closure. How do I do this? SyncViewController.swift import UIKit class SyncViewController: UIViewController,

问题 I created a class than makes implementing a picker view easier for the developer. In the UIPickerView Datasource methods, I'm returning the values from a closure. Example: func pickerView(pickerView: UIPickerView, numberOfRowsInComponent component: Int) -> Int { return pickerNumberOfRows!(component: component) } I am using the same thing for all datasource methods. When I run the app, it shows the picker on screen with no data. The problem is I'm receiving data from the closure which in turn

问题 I'm rather new at swift and have been doing some research on how to answer this question myself since I want to learn, but I am completely stumped. I have a function which requests data from a server, and after the data is received, a completion handler is executed which parses the data. Within the previously mentioned completion handler, another function is called which is passed a completion handler itself. For some reason, the function call within the function is being being skipped, and

问题 I really liked Sulthan's answer (in Anonymous class in swift) which describes building an object which conforms to a protocol but whose class is hidden inside a closure. This would be nice for building singletons and not polluting the name-space with classes like Recorder1, Recorder2... However, when I try to do anything useful with it, I fail because the closure will not close over the outer class' instance members inside the inner class. protocol EventListener { func handleEvent(event: Int)