Need to distinguish between iPhone3x and iPhone4x. Is there any way to figure out the version from JavaScript please? You can use navigator.userAgent to check the OS version, but that isn't really the problem here. What you can do is use media queries to check the actual screen resolution of the device, which might be the cause of the problem at hand. var isRetina = window.matchMedia("(
需要区分iPhone3x和iPhone4x。 有什么方法可以从JavaScript中找出版本吗？ 您可以使用navigator.userAgent来检查操作系统版本，但这不是真正的问题。 你可以做的是使用媒体查询来检查设备的实际屏幕分辨率，这可能是手头问题的原因。 var isRetina = window.matchMedia("(-webkit-min-device-pixel-ratio: 2)").matches; 您也可以不使用JavaScript，通过使用媒体查询为视网膜显示加载不同的样式表： <link rel="styles
I would like to detect whether the user has pressed Enter using jQuery. How is this possible? Does it require a plugin? EDIT: It looks like I need to use the keypress() method. I wanted to know if anyone knows if there are browser issues with that command - like are there any browser compatibility issues I should know about? The whole point of jQuery is that you don't have to worry a
我想检测用户是否使用jQuery按Enter 。 这怎么可能？ 它需要一个插件吗？ 编辑：它看起来像我需要使用keypress()方法。 我想知道是否有人知道该命令是否存在浏览器问题 - 就像我应该知道的浏览器兼容性问题一样？ jQuery的重点是你不必担心浏览器的差异。 我确信你可以安全地在所有浏览器中输入13。 所以考虑到这一点，你可以这样做： $(document).keypress(function(e) { if(e.which == 13) { alert('Yo
Click here to view image Step1) I am drawing an image of 1920*1080 to canvas1 with the drawImage(image,0,0); setp2) Now i am taking another logo image and drawing it to another canvas called canvas2 with the drawImage(logo,0,0); I used fabricjs to for logo drag able and re sizable functionalities. Step3) Then i am drawing canvas1 & canvas2 to another canvas called canvas3 and download
点击此处查看图片 Step1）我使用drawImage（image，0,0）将1920 * 1080的图像绘制到canvas1; setp2）现在我正在使用另一个徽标图像并将其绘制到另一个名为canvas2的画布上，画布的图标（logo，0,0）; 我使用fabricjs来实现可拖拽标志和可重新定义的功能。 Step3）然后我将canvas1＆canvas2绘制到另一个名为canvas3的画布并下载它。 在这种情况下，除了图像显示较大（1920 * 1080）以外，一切都很好。 为了用户体验，
I'm trying to convert a large SVG (it's data URL is about 750000 - 1000000 characters) to a PNG by passing it's data url through an image and into a canvas but the image is only loading about 1/4 of the SVG. Creating via: var svg_xml = (new XMLSerializer()).serializeToString(svg), url = 'data:image/svg+xml;base64,' + btoa(svg_xml); var img = new Image(); img.width = 730; img.h
我试图通过将一个大的SVG（它的数据URL大约是750000 - 1000000个字符）转换为PNG，方法是将其数据url传递到一个图像并放入一个画布中，但该图像仅加载大约四分之一的SVG。 创建通过： var svg_xml = (new XMLSerializer()).serializeToString(svg), url = 'data:image/svg+xml;base64,' + btoa(svg_xml); var img = new Image(); img.width = 730; img.height = 300; img.onload = function(){ var canvas = docume
Is it possible to capture or print what's displayed in an html canvas as an image or pdf? I'd like to generate an image via canvas, and be able to generate a png from that image. Oops. Original answer was specific to a similar question. This has been revised: var canvas = document.getElementById("mycanvas"); var img = canvas.toDataURL("image/png"); with the value in IMG you can
是否可以捕获或打印HTML画布中显示的图像或PDF？ 我想通过画布生成一个图像，并能够从该图像生成一个PNG。 哎呀。 原始答案是针对类似问题的。 这已经修改： var canvas = document.getElementById("mycanvas"); var img = canvas.toDataURL("image/png"); 与IMG中的值，你可以把它写成一个新的图像，如下所示： document.write('<img src="'+img+'"/>'); HTML5提供了在Opera，Firefox和Safari 4 beta中实现
How does Array.prototype.sort handle undefined values in an array? var array = [1,undefined,2,undefined,3,undefined,4]; var array2 = []; array2[0] = 1;array2[2] = 2;array2[4] = 3;array2[6] = 4; When calling array.sort(function(l,r) { ... }); The values undefined are never passed in as l or r . Can I guarantee that all the undefined values will always go to the end of the array for all browse
Array.prototype.sort如何处理数组中的未定义值？ var array = [1,undefined,2,undefined,3,undefined,4]; var array2 = []; array2[0] = 1;array2[2] = 2;array2[4] = 3;array2[6] = 4; 当调用array.sort(function(l,r) { ... }); undefined的值永远不会以l或r传入。 我能保证所有未定义的值总是会到达所有浏览器的数组末尾吗？ 以下循环会处理数组中的所有非undefined数据吗？ array.sort(); for (var i = 0; array[i]
How do I trigger an update to child elements when a parent observable changes using KnockoutJs? In my application, I'm building a translation tool. I have a knockout class that represents the raw (default) value of some text, with a collection of translated children: function ParentObject(id, defaultValue) { var self = this; self.id = id; self.defaultValue = ko.observable(def
当使用KnockoutJs改变父级observable时，如何触发子元素的更新？ 在我的应用程序中，我正在构建一个翻译工具。 我有一个挖空类，它代表了一些文本的原始（默认）值，并带有一些已翻译的孩子的集合： function ParentObject(id, defaultValue) { var self = this; self.id = id; self.defaultValue = ko.observable(defaultValue); self.children = ko.observableArray(); self.loadChildren = functio
(I'm a bit new to javascript and the whole prototype/inheritance concept, so my apologies if this is a dumb question) In my codebase, I've got a mishmash of Revealing-Module-Pattern type of objects, and then I've also got objects that use the Constructor-Pattern (where instances get newed-up). I also have a block of code (written in the constructor-type-pattern) which provides Eve
（我对JavaScript和整个原型/继承概念有点新，所以如果这是一个愚蠢的问题，我很抱歉） 在我的代码库中，我得到了Revealing-Module-Pattern类型的对象的混杂，然后我也得到了使用构造器模式的对象（其中的实例变得更新）。 我也有一块代码（用constructor-type-pattern编写）提供了EventEmitter功能。 是否可以将此代码用作构造函数模式对象和显示模块模式对象的基类？ 试图做到这一点甚至是有道理的？ 首先，只有“const
I have been reading about revealing module pattern in Addy Osmani's book. It highlights following disadvantage: A disadvantage of this pattern is that if a private function refers to a public function, that public function can't be overridden if a patch is necessary. This is because the private function will continue to refer to the private implementation and the pattern doesn't a
我一直在阅读关于Addy Osmani书中revealing module pattern 。 它突出了以下缺点： 这种模式的一个缺点是，如果一个私有函数引用一个公共函数，那么如果补丁是必要的，则该公共函数不能被覆盖。 这是因为私有函数将继续引用私有实现，并且该模式不适用于公共成员，而仅适用于函数。 引用私有变量的公共对象成员也受上述无补丁规则注释的约束。 因此，使用“展现模块”模式创建的模块可能比使用原始模块模式创建的模块更脆
I was searching of way to define a class in JavaScript. I came up with hybrid Module and Prototype pattern, but not sure if I don't miss something. Basically I wanted to use 'this' keyword. Example: var A = function() { this.x = 10; }; A.prototype = (function() { function privatePrint() { alert("Printing from private! x:" + this.x); }
我正在寻找用JavaScript定义一个类的方法。 我想出了混合模块和原型模式，但不知道如果我不想错过什么。 基本上我想用'this'关键字。 例： var A = function() { this.x = 10; }; A.prototype = (function() { function privatePrint() { alert("Printing from private! x:" + this.x); } this.print = function() { privatePrint.call(this);