Javascript IE 检测,为什么不使用简单的条件注释? [英] Javascript IE detection, why not use simple conditional comments?
问题描述
为了检测 IE,大多数 Javascript 库会做各种各样的把戏.
In order to detect IE most Javascript libaries do all sort of tricks.
- jQuery 似乎在页面的 DOM 中添加了一个临时对象来检测某些功能,
- YUI2 在其
YAHOO.env.ua = function()
(文件yahoo.js
) 中对用户代理执行正则表达式
- jQuery seem to add a temporary object into your pages's DOM to detect some features,
- YUI2 does regex on the user agent in its
YAHOO.env.ua = function()
(fileyahoo.js
)
阅读这个答案后我想到这是真的,为了在 Javascript 中简单地检测 IE,我们可以简单地添加到我们的页面中:
After reading this answer it came in my mind that it's true, in order to detect simply IE in Javascript we could simply add to our pages:
<!--[if IE]><script type="text/javascript">window['isIE'] = true;</script><![endif]-->
<script type="text/javascript" src="all-your-other-scripts-here.js"></script>
现在 window.isIE
变量已为我们所有的 Javascript 代码设置,只需执行以下操作:
Now the window.isIE
variable is set for all our Javascript code, by simply doing:
if(window.isIE)
...
除了这可能会导致痛苦,因为它必须添加到所有页面中,还有什么我可能不知道的问题/注意事项吗?
Beside the fact that this might result in being a pain because it has to be added in all pages, are there any issues/considerations I might be unaware of?
仅供参考:我知道最好使用对象检测而不是浏览器检测,但在某些情况下,您仍然需要使用浏览器检测.
FYI: I know it's better to use object detection rather than browser detection, but there are cases where you still have to use browser detection.
推荐答案
James Padolsey 在 GitHub 上放了一个小片段 我将在这里引用:
James Padolsey put a little snippet on GitHub that I'll quote here:
// ----------------------------------------------------------
// A short snippet for detecting versions of IE in JavaScript
// without resorting to user-agent sniffing
// ----------------------------------------------------------
// If you're not in IE (or IE version is less than 5) then:
// ie === undefined
// If you're in IE (>=5) then you can determine which version:
// ie === 7; // IE7
// Thus, to detect IE:
// if (ie) {}
// And to detect the version:
// ie === 6 // IE6
// ie > 7 // IE8, IE9 ...
// ie < 9 // Anything less than IE9
// ----------------------------------------------------------
// UPDATE: Now using Live NodeList idea from @jdalton
var ie = (function(){
var undef,
v = 3,
div = document.createElement('div'),
all = div.getElementsByTagName('i');
while (
div.innerHTML = '<!--[if gt IE ' + (++v) + ']><i></i><![endif]-->',
all[0]
);
return v > 4 ? v : undef;
}());
当然,所有的功劳都应该归詹姆斯所有,我只是信使(但如果我的复制粘贴操作出错,请射击信使).
Of course all credits should go to James, I'm only the messenger (but please shoot the messenger if my copy-paste action erred).
还要查看创建的分叉.Paul Irish 在评论中解释了内部运作.
Also look at the forks that were created. Paul Irish explained the inner workings in a comment.
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