Using javascript to determine the IE version number is simple, practical and backward compatible_javascript skills

Today I need to determine the IE version number in a project, and because jQuery 2.0 removes the judgment of the browser version number (it recommends feature detection), I saw a piece of code written by a foreigner:

Copy code The code is as follows:

var _IE = (function(){
var v = 3, div = document.createElement ('div'), all = div.getElementsByTagName('i');
while (
div.innerHTML = '',
all[0]
);
return v > 4 ? v : false ;
}()) ;

This code is really clever! Both brief and backward compatible! The general approach is: regular search for USER_AGENT;
However, due to historical reasons, USER_AGENT has always been inaccurate and has been changed in a mess by major manufacturers.

For example:

Copy code The code is as follows:

IE10: Mozilla/ 5.0 (compatible; MSIE 10.0; Windows NT 6.2; WOW64; Trident/6.0)
IE11 : Mozilla/5.0 (Windows NT 6.3; Trident/7.0; rv 11.0) like Gecko

These What kind of messy strings are they? . . Who knows what IE12 will become! ! !
So using feature detection or USER-AGENT detection is neither reliable nor backwards compatible!

Highly recommend the above code!
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When I first learned programming, I felt that I knew a lot and had a lot to write about;
But after really learning a lot of knowledge in depth, I painfully discovered that I knew too little! I want to write something, but it’s hard to do it.