We have a single page application which we ship changes to on a regular basis. On rare occasion, a version of the client has a bug and submits a bad request to the server. Even after you ship out an update, there's a possibility old versions of the client can linger. In these circumstances, it would be useful for the client to send a version identifier along with our requests so that we k
我们有一个单页面应用程序，我们会定期发送更改。 在极少数情况下，客户端版本会有错误并向服务器提交错误的请求。 即使在您发布更新之后，客户端的旧版本仍有可能徘徊。 在这些情况下，客户端发送版本标识符以及我们的请求对我们很有用，以便我们知道哪个版本的代码库启动了它。 这种情况下是否有现有的最佳做法？ 附加一个额外的标题看起来像是一个简单的解决方案，但如果这个问题已经得到解决，我不想开创新局面。
I'm developing a VM in JavaScript and need to multiply two signed 32-bit numbers with a 64-bit signed result stored as two 32-bit signed numbers (upper 32-bit and lower 32-bit). I managed to do the same for unsigned numbers by splitting both numbers to 16-bit pairs and multiplying those: a*b = (ah * 2^16 + al) * (bh * 2^16 + bl) : function mul_32_unsigned( a, b ) { var ah = a >>>
我正在JavaScript中开发一个虚拟机，并且需要将两个带符号的32位数字与64位有符号结果相乘，作为两个32位有符号数字（高位32位和低位32位）存储。 我设法对无符号数做同样的操作，将两个数分成16位对并乘以： a*b = (ah * 2^16 + al) * (bh * 2^16 + bl) ： function mul_32_unsigned( a, b ) { var ah = a >>> 16; var bh = b >>> 16; var al = a & 0xFFFF; var bl = b & 0xFFFF; var m
I have a piece of Javascript code I'm trying to understand // read big-endian (network byte order) 32-bit float readFloat32 = function(data, offset) { var b1 = data.charCodeAt(offset) & 0xFF, b2 = data.charCodeAt(offset+1) & 0xFF, b3 = data.charCodeAt(offset+2) & 0xFF, b4 = data.charCodeAt(offset+3) & 0xFF; var sign = 1 - (2*(b1 >> 7));
我有一段Javascript代码，我试图理解 // read big-endian (network byte order) 32-bit float readFloat32 = function(data, offset) { var b1 = data.charCodeAt(offset) & 0xFF, b2 = data.charCodeAt(offset+1) & 0xFF, b3 = data.charCodeAt(offset+2) & 0xFF, b4 = data.charCodeAt(offset+3) & 0xFF; var sign = 1 - (2*(b1 >> 7)); //<--- here it is an
In Node.js it is, for several reasons, customary/recomended to pass a callback to a function as the last argument. There may also be one or more optional arguments, which we would like to pass before the callback. You end up with seeing a lot of very repetitive code, such as // receiveMessages([options], [callback]) function receiveMessages(options, callback) { if(typeof options === 'functi
在Node.js中，出于多种原因，习惯/推荐将回调传递给函数作为最后一个参数。 可能还有一个或多个可选参数，我们希望在回调之前传递这些参数。 你最终会看到很多非常重复的代码，比如 // receiveMessages([options], [callback]) function receiveMessages(options, callback) { if(typeof options === 'function'){ callback = options; options = {}; // or some other sensible default } //... } 添
I would like to create a secure postMessage connection (origin safe), with an Iframe that is created at runtime. Current state: I have a script, that generates an iframe with a specific domain ( domain.b.com in the example below). I want that iframe to receive messages only from the parent domain (the page that included my script). Since the parent domain is unknown at runtime, I'm thinki
我想创建一个安全的postMessage连接（原点安全），并在运行时创建一个Iframe。 当前状态：我有一个脚本，它会生成一个具有特定域的iframe（下domain.b.com中的domain.b.com ）。 我希望iframe只接收来自父域（包含我的脚本的页面）的消息。 由于父域在运行时是未知的，因此我正在考虑如下所述的“握手”过程： 等待Iframe被加载。 发送来自父域的postMessage及其来源。 将允许的原点设置为第一个接收原点 编辑：更多
I am currently working on an image editor and stumbled over this weird behaviour regarding pixel manipulation and/or function calls in V8. http://jsperf.com/canvas-pixelwise-manipulation-performance There are two test cases. Both test cases should manipulate the image data of an in-memory canvas to increase the brightness. So they have to iterate over every pixel and manipulate the 4 color
我目前正在研究一个图像编辑器，并偶然发现了这个有关V8中像素操作和/或函数调用的奇怪行为。 http://jsperf.com/canvas-pixelwise-manipulation-performance 有两个测试用例。 这两个测试用例都应该处理内存中的画布的图像数据以增加亮度。 所以他们必须迭代每个像素并操纵每个像素的4个颜色值。 情况1 情况1执行“总共1个函数调用”，这意味着它将上下文和imageData传递给函数，然后迭代像素并操作数据。 全部在一个
Possible Duplicate: javascript - Array.map and parseInt I saw this example of strange JavaScript behavior on twitter ['10','10','10','10','10'].map(parseInt) evaluates to [10, NaN, 2, 3, 4] could somebody explain this behavior? I verified it in chrome and firebug ['10','10','10','10','10'].map(function(x){return parseInt(x);}) correctly returns an array of 10s as integers. Is this an
可能重复： javascript - Array.map和parseInt 我在twitter上看到了这个奇怪的JavaScript行为的例子 ['10','10','10','10','10'].map(parseInt) 评估为 [10, NaN, 2, 3, 4] 有人可以解释这种行为吗？ 我用铬和萤火虫对它进行了验证 ['10','10','10','10','10'].map(function(x){return parseInt(x);}) 正确地返回一个10的数组作为整数。 这是不恰当的使用map（），parseInt的错误还是其他？ parseInt接收两个参
Enumerating the keys of javascript objects replays the keys in the order of insertion: > for (key in {'z':1,'a':1,'b'}) { console.log(key); } z a b This is not part of the standard, but is widely implemented (as discussed here): ECMA-262 does not specify enumeration order. The de facto standard is to match insertion order, which V8 also does, but with one exception: V8 gives no guarante
枚举javascript对象的键以插入顺序重放键： > for (key in {'z':1,'a':1,'b'}) { console.log(key); } z a b 这不是标准的一部分，但被广泛实施（如此处所述）： ECMA-262不指定枚举顺序。 事实上的标准是匹配V8的插入顺序，但有一个例外： V8对数组索引的枚举顺序（即可以解析为32位无符号整数的属性名称）不作任何保证。 构建Node.js库时，是否可以接受这种行为？ 绝对不！ 这不是一个风格问题，而是一个正确的
我知道它用于使参数成为一个真正的数组，但我不明白使用Array.prototype.slice.call(arguments)时会发生什么情况。 What happens under the hood is that when .slice() is called normally, this is an Array, and then it just iterates over that Array, and does its work. How is this in the .slice() function an Array? Because when you do: object.method(); ...the object automatically becomes the value of th
我知道它用于使参数成为一个真正的数组，但我不明白使用Array.prototype.slice.call(arguments)时会发生什么情况。 在引擎盖下发生的是，当.slice()被正常调用时， this是一个数组，然后它只是迭代该数组，并完成它的工作。 如何为this在.slice()函数对数组？ 因为当你这样做时： object.method(); ...的object自动成为的值this在method() 所以： [1,2,3].slice() ...的[1,2,3]数组被设置为的值this在.slice() 但是如
I've been looking for some information regarding the scrapped ECMAScript 4th Edition without much success, even on SO. I know Mozilla's JavaScript 1.7 implemented many (all?) of the new features offered in 4th Edition and I thought I remembered a good John Resig post on it but I can't seem to find it on his blog now. In particularly, I want to know why it was completely scrapped in
我一直在寻找一些关于废弃的ECMAScript第四版的信息，即使在SO上也没有取得太大的成功。 我知道Mozilla的JavaScript 1.7实现了第4版中提供的许多（全部）新功能，并且我想我记得有一个很好的John Resig的文章，但我现在似乎无法在他的博客上找到它。 特别是，我想知道为什么它完全取消了ECMA-262第5版，并且为什么它不仅仅得到了改进。 一些特性非常酷，比如生成器，迭代器，let，新赋值操作符和（我特别喜欢的）解构赋值。