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ECMAScript 5 Strict Mode

A strict alignment of code elements related to a particular topic is often used to visually reinforce the importance of that topic for the reader.

Last updated on : 2025-11-11

Browser Versions

IE

Edge

Firefox

Chrome

Safari

Opera

5.5 - 9

10 - 11

12 - 142

2 - 3

4 - 147

4 - 12

13 - 145

3.2 - 4

5.1 - 5

6.1 - 26.2

9.5 - 11

11.6 - 122

Fully Supported

Partially

No Support

Browser Compatibility

ECMAScript 5 Strict Mode on IE is fully supported on 10-11, and not supported on 5.5-9 IE versions.

ECMAScript 5 Strict Mode on Edge is fully supported on all Edge versions.

ECMAScript 5 Strict Mode on Firefox is fully supported on 4-147, and not supported on 2-3 Firefox versions.

ECMAScript 5 Strict Mode on Chrome is fully supported on 13-145, and not supported on 4-12 Chrome versions.

ECMAScript 5 Strict Mode on Safari is fully supported on 6.1-26.2, partially supported on 5.1-5, and not supported on 3.2-4 Safari versions.

ECMAScript 5 Strict Mode on Opera is fully supported on 11.6-122, and not supported on 9.5-11 Opera versions.

ECMAScript 5 Strict Mode on Safari on iOS is fully supported on 5-26.1, and not supported on 3.2-4 Safari on iOS versions.

ECMAScript 5 Strict Mode on Android Browser is fully supported on 3-142, and not supported on 2.3-2.1 Android Browser versions.

ECMAScript 5 Strict Mode on Opera Mobile is fully supported on 11.5-80, and not supported on 10-11 Opera Mobile versions.

ECMAScript 5 Strict Mode on Chrome for Android is fully supported on all Chrome for Android versions.

ECMAScript 5 Strict Mode on Firefox for Android is fully supported on all Firefox for Android versions.

ECMAScript 5 Strict Mode on Samsung Internet is fully supported on all Samsung Internet versions.

Browser Support for ECMAScript 5 Strict Mode

ECMAScript 5 Strict Mode on Chrome

ECMAScript 5 Strict Mode on Safari

ECMAScript 5 Strict Mode on Firefox

ECMAScript 5 Strict Mode on Internet Explorer

ECMAScript 5 Strict Mode on Opera

ECMAScript 5 Strict Mode on Edge

References

Data sourced from

97

High

Overall Browser Compatibility Score

Note:ECMAScript 5 Strict Mode shows a browser compatibility score of 97. This is a collective score out of 100 to represent browser support of a web technology. The higher this score is, the greater is the browser compatibility. The browser compatibility score is not a 100% reflection for every browser and the web technology support. However, it does give you an estimate on how much you should rely on a particular web technology in terms of browser compatibility.

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