使用 Javascript 检测 websocket 支持的最佳方法是什么？
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What is the best way to detect websocket support using Javascript?
提问by Steven
I'm trying to use Javascript to detect if a web browser supports websockets, but using only feature-based detection, I'm getting false positives, so I added a user agent test to throw out Android devices instead, which I'm not happy about. I have a Samsung Galaxy Tab 2, and here's my detection code:
我正在尝试使用 Javascript 来检测 Web 浏览器是否支持 websockets，但仅使用基于功能的检测，我得到了误报，所以我添加了一个用户代理测试来代替 Android 设备，但我不是高兴。我有一个三星 Galaxy Tab 2，这是我的检测代码：
var isSupported = (("WebSocket" in window && window.WebSocket != undefined) ||
("MozWebSocket" in window));
/* This line exists because my Galaxy Tab 2 would otherwise appear to have support. */
if (isSupported && navigator.userAgent.indexOf("Android") > 0)
isSupported = false;
if (isSupported)
document.write("Your browser supports websockets");
else
document.write("Your browser does not support websockets");
This code seems to work with IE, Firefox, Safari (including iPhone/iPad), and Chrome. However, the feature-based check is returning true when I use the default browser of my Samsung Galaxy Tab 2, which is incorrect because that browser does not actually support websockets. Furthermore, I don't know how many other Android devices have this same issue, so at the moment, this is the best solution I'm aware of for detection.
此代码似乎适用于 IE、Firefox、Safari（包括 iPhone/iPad）和 Chrome。但是，当我使用 Samsung Galaxy Tab 2 的默认浏览器时，基于功能的检查返回 true，这是不正确的，因为该浏览器实际上不支持 websocket。此外，我不知道有多少其他 Android 设备有同样的问题，所以目前，这是我所知道的最好的检测解决方案。
Is there a better way to detect websocket support other than what I'm doing? I do realize that workarounds exist for Android, such as using a different browser, which means my user agent detection code as-is would not be a good thing. My goal is to not have to rely on the user agent in the first place.
除了我正在做的事情之外，有没有更好的方法来检测 websocket 支持？我确实意识到 Android 存在解决方法，例如使用不同的浏览器，这意味着我的用户代理检测代码原样不是一件好事。我的目标是首先不必依赖用户代理。
Any suggestions?
有什么建议？
回答by Isaiah Turner
This is the shortest solution and is used by Modernizr. Simply add this to your code
这是最短的解决方案，由 Modernizr 使用。只需将此添加到您的代码中
supportsWebSockets = 'WebSocket' in window || 'MozWebSocket' in window;
then you can use it by running
然后你可以通过运行来使用它
if (supportsWebSockets) {
// run web socket code
}
回答by Rob M.
I think the Modernizr library is what you are looking for: http://modernizr.com/
我认为 Modernizr 库正是您要找的：http: //modernizr.com/
Once you include the library on your page, you can use a simple check like:
在页面上包含库后，您可以使用简单的检查，例如：
if(Modernizr.websockets){
// socket to me baby
}
回答by jfaron
after reading @gzost's response.. I started tinkering.. since nothing else can properly detect WS's on my android phone... even websocket.org says i have it, but then fails to connect.
阅读@gzost 的回复后.. 我开始修修补补.. 因为没有其他东西可以正确检测我的 android 手机上的 WS ......甚至 websocket.org 说我有它，但后来无法连接。
Anyways, try this workaround.. seems to properly detect it on/off with chrome, FF, safari and the default android browser.
无论如何，试试这个解决方法.. 似乎可以使用 chrome、FF、safari 和默认的 android 浏览器正确检测它的开/关。
var has_ws=0;
function checkWebSocket(){
try{
websocket = new WebSocket("ws:websocket.org");
websocket.close('');
}catch(e){ //throws code 15 if has socket to me babies
has_ws=1;
}
}
$(document).ready(function(){
checkWebSocket();
});
回答by kroko
This page comes on top in google search.
此页面在谷歌搜索中名列前茅。
In year 2016 cutting the mustard for modern WebSockets implementation (no prefixes such as MozWebSocket) would be
在 2016 年为现代 WebSockets 实现（没有前缀，例如MozWebSocket）削减芥末将是
if (
'WebSocket' in window && window.WebSocket.CLOSING === 2
) {
// supported
}
回答by cskwg
None of the above answers by itself was sufficient in my tests. The following code seems to be working fine:
在我的测试中，上述答案本身都不够。以下代码似乎工作正常：
function nll( o ) { return CS.undefined === typeof o || null === o; }
// ...
function check_ws_object() {
try {
var websocket = new WebSocket( "wss://echo.websocket.org" );
return true;
} catch ( e ) { ; }
return false;
}
//
function check_support() {
if ( !( WebSocket in window ) ) {
if ( nll( window.WebSocket) ) {
if ( !this.check_ws_object() ) {
alert( "This browser doesn't support HTML5 Web Sockets!" );
return false;
}
}
}
return true;
},
The above tests are sorted, so that the faster ones come first.
上面的测试是排序的，所以速度快的先到。
