JavaScript determines whether the browser is IE

As a front-end developer, I can’t avoid IE’s pitfalls. Other browsers are fine, but IE is broken. There is no support for various things. I’m convinced.

Some properties and methods are not supported by all versions of IE, while some are partially supported. In the project, the main dividing line is IE8. I believe that most of the projects currently under maintenance and development support IE8 and above. So this article briefly summarizes how to determine whether the browser is IE and its version is 8.0.

First of all, some properties and methods are not supported by all versions of IE, so you only need to determine whether it is IE

The following three are the methods I used in my project. If there are new methods, they will be updated. If you have other better methods, please feel free to share them~~

• document.all
• window.ActiveXObject
• window.navigator.msSaveOrOpenBlob

//Choose one function isIE(){
 // It is said that Firefox will add the document.all method in the future, so it is recommended to use the other two methods if (document.all) return true; 
 
 if (!!window.ActiveXObject || "ActiveXObject" in window) return true; 
 
 if (window.navigator && window.navigator.msSaveOrOpenBlob) return true; 
}

Determine if the browser is IE8 or below

As I mentioned above, most of the projects under maintenance and development only support IE8 and above.

navigator.userAgent

function isIE8(){
 var DEFAULT_VERSION = 8.0; 
 var ua = navigator.userAgent.toLowerCase(); 
 var isIE = ua.indexOf("msie")>-1; 
 var safariVersion; 
 if(isIE){ 
  safariVersion = ua.match(/msie ([\d.]+)/)[1]; 
 } 
 if (safariVersion <= DEFAULT_VERSION ) { 
  return true 
 };
}

If you have special requirements and need to be compatible with lower versions, then:

var isIE = !!window.ActiveXObject; 

var isIE6 = isIE && !window.XMLHttpRequest; 

var isIE8 = isIE && !!document.documentMode; 

var isIE7 = isIE && !isIE6 && !isIE8;

CSS properties not supported by IE8 and below

• box-shadow
• linear-gradient
• Prompt placeholder
• Transparency rgba
• border-image
• border-radius
• Rotation-related transform
  

Methods not supported by IE

Browse PDF files online. Since IE does not have a built-in PDF reader, you can only download and view them.

• When the backend returns a file stream: window.navigator.msSaveOrOpenBlob(blob); For details, please refer to the other two blog posts.
• JavaScript processes the PDF file stream returned by the backend, and previews and downloads the PDF file online
• Vue.js +pdf.js processes the response pdf file stream data, and the front-end image preview cannot be downloaded
  

The download attribute of the <a> tag is not supported, so you can create a new iframe and set its src attribute

if (isIE()){
	$("a").bind('click',function(){
		var elemIF = document.createElement("iframe"); 
		elemIF.src = FilePath;
		elemIF.style.display = "none"; 
		document.body.appendChild(elemIF);
	});
} else {
	$("a").attr("href",FilePath).attr("download",FileName);
}

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