Is Using `navigator.appName` and `navigator.appVersion` Reliable for Detecting Older IE Versions?-JS Tutorial-php.cn

Is Using `navigator.appName` and `navigator.appVersion` Reliable for Detecting Older IE Versions?

Mary-Kate Olsen

Release： 2024-11-06 14:54:02

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Is Using `navigator.appName` and `navigator.appVersion` Reliable for Detecting Older IE Versions?

Detect IE Version (Prior to v9) in JavaScript

Detection Criteria and Proposed Code

To determine if a user is accessing a website using a version of Internet Explorer prior to v9, the proposed code leverages the navigator.appName and navigator.appVersion properties.

if (navigator.appName.indexOf("Internet Explorer") != -1) {
    // User is using IE
    // Check for IE version < 9
}

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Will This Code Do the Trick?

Despite addressing the concerns raised about user agent string spoofing and feature support detection, the proposed code has several limitations:

Conditional statements: While conditional statements are useful for targeting different IE versions, they are only supported in IE5-9, so this approach is obsolete in modern browsers.
Precision (IE 1 and IE 10 ): The code fails to detect IE 1 and IE versions greater than or equal to 10.
Completeness: The code only checks for IE versions less than 9, ignoring potential edge cases.

A Preferred Alternative

To overcome these limitations, a more comprehensive approach involves using CSS class-based detection:

Define CSS classes that represent different IE versions, e.g.:

html.lt-ie9 { ... }
html.lt-ie8 { ... }
html.lt-ie7 { ... }

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Apply these classes to the element based on the detected IE version:
```



 <html> 
```
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1. Use CSS to specify styles specific to the detected IE version, or implement JavaScript logic based on the assigned class:
```
if ($('html').is('.lt-ie7, .lt-ie8, .lt-ie9')) {
    // IE version < 9
} else {
    // Other browsers
}
```
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This method provides more flexibility, compatibility, and control for handling different browser versions.
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