what does 'this' refer to in Javascript functions

I understand the general idea behind the this keyword but I'm having trouble figuring out what it actually refers to in practice. For example, in both these example exercises, I guessed the wrong number. for question1, I said that the alert would be '5', because it is referring to the this.x outside the anonymous function in the function. In question2, I thought the alert would b

Javascript中的'this'是指什么

我理解this关键字背后的一般想法,但我在实践中很难弄清楚它实际上指的是什么。 例如,在这两个示例练习中,我猜错了数字。 对于question1,我说alert是'5',因为它指的是函数中匿名函数之外的this.x。 问题2中,我认为警报将是5,因为这条线 var alertX = o.alertX; 将变量o中属性x的值5绑定到新变量'alertX',该变量将成为下一行中的函数调用:alertX(); 你能解释我为什么错了吗? var question1 =

Adding a Quiz Timer, Fade Out/Skip to the next if timer reaches 0

I'm really new to jQuery but familiar with some other languages. I recently bought a quiz type script and I'm trying to add a simple 15 second timer to each question. It's only a fun quiz, so no need to worry about users playing with the javascript to increase time etc. Basically, if a user does not pick a question within 15 seconds, it will automatically go on to the next questio

添加测验计时器,淡出/如果计时器达到0,跳到下一个

我对jQuery非常陌生,但熟悉一些其他语言。 我最近买了一个测验类型的脚本,我试图给每个问题添加一个简单的15秒计时器。 这只是一个有趣的测验,所以不用担心用户使用JavaScript来增加时间等。 基本上,如果用户在15秒内没有选择一个问题,它会自动进入下一个问题,定时器重新开始。 答案有.next标记,当选择它时,将转到下一个问题,如下面的代码所示(希望)。 superContainer.find('.next').click(function () {

Performance overhead of javascript libraries

Does anyone know if there are studies done that show the performance overhead of using javascript libraries (other than the obvious of their download time) vs using just basic javascript? The libraries are so huge these days and I was curious. From my computer science degree it seems it should have growth n. (in other words linear). In computer science terms this is non threatening but how

JavaScript库的性能开销

有谁知道是否有研究表明,使用JavaScript库的性能开销(除了明显的下载时间)vs使用基本的JavaScript? 这些日子里图书馆非常大,我很好奇。 从我的计算机科学学位看,它应该有增长n。 (换句话说是线性的)。 在计算机科学方面,这不是威胁性的,但它是如何实际影响页面加载时间和页面性能的毫秒? 我知道CPU是一个问题,RAM等等。 但是有没有可以测试这些事情的测试? 我知道另一个因素是库经常被优化,以便以更低优

set text to google+ share button

I'm creating a page which has a g+ share button, but I wanted to dynamically change the description of the content to share. to customize the share button I am using the snippet with Open Graph protocol. The solution I tried was the following, but it did not work correctly: <meta property="og:title" content="O Fabuloso Gerador De Lero Lero v3" /> <meta property="og:image" content

将文本设置为Google +分享按钮

我正在创建一个拥有g +分享按钮的页面,但我想动态更改要共享的内容描述。 自定义共享按钮我正在使用Open Graph协议的片段。 我尝试的解决方案如下,但无法正常工作: <meta property="og:title" content="O Fabuloso Gerador De Lero Lero v3" /> <meta property="og:image" content="images/robot.png" /> <meta property="og:description" content="..." /> $('meta[property="og:description"]').attr(

best plugin for charts

Which is the best plugin to make charts with Cordova(Phonegap)? (besides the jquery mobile plugin) I have tried diferents, but on web pages, I don't know how works on mobile for example Flotr2 or HighChart Check this answer: Phonegap + jQuery Mobile + Stock / Line Chart And this: https://groups.google.com/forum/?fromgroups=#!topic/phonegap/7sX9b2dQLQg I'd go with flot. ZoomCha

图表的最佳插件

使用Cordova(Phonegap)制作图表的最佳插件是哪一个? (除了jQuery的手机插件) 我曾尝试diferents,但在网页上,我不知道如何在移动设备上工作,例如Flotr2或HighChart 检查这个答案:Phonegap + jQuery Mobile +股票/折线图 而且:https://groups.google.com/forum/?fromgroups=#!topic/phonegap/7sX9b2dQLQg 我会用flot去。 ZoomCharts是一个新的图表和图表库,它将JavaScript图表和图表同时引入桌面和移动设备

magnetic div: fixed div inside absolute positioned div

I have the following page: [LINK] The page is designed to be scrolled horizontally, so that a series of divs (black bordered ones) appear in a row. Now, I the smaller divs inside (red ones) to behave so that they never go outside the parent div but at the same time, while scrolling the page, I want them to move inside the parent div like if they were fixed-positioned. I'll explain mys

磁性div:在绝对定位div内的固定div

我有以下页面: [链接] 该页面被设计为水平滚动,以便连续出现一系列div(黑色边框)。 现在,我内部的较小的div(红色)表现为不会超出父div,但同时在滚动页面的同时,我希望它们在父div内移动,就像它们被固定位置一样。 我会用一个图解释自己。 我希望我的div的行为如下所示: [链接] 任何人都可以帮忙 谢谢你的时间! UPDATE 创建了一些最小/实验性的jQuery插件:https://gist.github.com/3177804 你

javascript based code editor for custom language syntax

I need javascript/html based code editor which I will customize for very simple custom coding language. This editor tools needs to work in an offline solution so the source code must be downloadable or open . Language syntax will be look like very simplified java script even with out variables I will define just 'if then' and 'built in function name' for the custom language.

定制语言语法的基于JavaScript的代码编辑器

我需要基于javascript / html的代码编辑器,我将自定义非常简单的自定义编码语言。 此编辑器工具需要在脱机解决方案中工作,因此源代码必须可下载或打开 。 语言语法看起来像非常简化的Java脚本,即使没有变量,我也会为自定义语言定义'if then'和'built in function name'。 所以它必须具有自定义编码语言语法的配置支持 如果你可以参考一些准备使用的解决方案,它将会非常有帮助 我为自己的问题找到

Samsung TV Video Caching using HTML5 and JS

I have to develop a Samsung TV application to play videos that are served from a remote server, which I don't have access to. Actually I've made an application to play videos of my own server. But my current requirements are as follows: I want to play videos that are served from a remote host (say //remote.com/video_id) to which I have no access, but my TV application is connected to

三星电视视频缓存使用HTML5和JS

我必须开发一个三星电视应用程序来播放从我无法访问的远程服务器提供的视频。 其实我已经制作了一个应用程序来播放我自己的服务器的视频。 但我目前的要求如下: 我想播放从远程主机(称为//remote.com/video_id)提供的视频,但我的电视应用程序已连接到我的服务器(如//myserver.com/samsungapp) 在播放之前,我必须在我的三星电视上缓存文件。 即缓冲100%然后播放 我使用HTML5和JS检查了FileApi和FileReader ,并

Overwrite a line in a file using node.js

What's the best way to overwrite a line in a large (2MB+) text file using node.js? My current method involves copying the entire file into a buffer. Spliting the buffer into an array by the new line character ( n ). Overwriting the line by using the buffer index. Then overwriting the file with the buffer after join with n . First, you need to search where the line starts and where

使用node.js覆盖文件中的一行

使用node.js覆盖大型(2MB +)文本文件中一行的最佳方式是什么? 我目前的方法涉及 将整个文件复制到缓冲区中。 按新行字符( n )将缓冲区分割成数组。 使用缓冲区索引覆盖该行。 然后在与n后用缓冲区覆盖文件。 首先,您需要搜索线路的起点和结束位置。 接下来,您需要使用一个函数来替换该行。 我有使用我的一个库的第一部分的解决方案:Node-BufferedReader。 var lineToReplace = "your_line_to_replace"; va

Array.prototype vs [] perf

Quick question that I haven't really had a chance to look into. Which is more performant when used in a call/apply sort of context: Array.prototype vs [] ? eg: function test1() { return Array.prototype.splice.apply(arguments, [1, 2]); } test1([1,2,3,4,5,6,7,8,9]); function test2() { return [].splice.apply(arguments, [1, 2]); } test1([1,2,3,4,5,6,7,8,9]); My thoughts: I would a

Array.prototype vs [] perf

快速的问题,我没有真正有机会进行调查。 在调用/应用类型的上下文中使用哪个更高性能: Array.prototype vs [] ? 例如: function test1() { return Array.prototype.splice.apply(arguments, [1, 2]); } test1([1,2,3,4,5,6,7,8,9]); function test2() { return [].splice.apply(arguments, [1, 2]); } test1([1,2,3,4,5,6,7,8,9]); 我的想法:我会假设Array.prototype方式更Array.prototype因为原型函数可以