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Lookbehind in JS regular expressions

- OTHER

The positive lookbehind ((?<= )) and negative lookbehind ((?<! )) zero-width assertions in JavaScript regular expressions can be used to ensure a pattern is preceded by another pattern.

Chrome

  1. ❌ 4 - 61: Not supported
  2. ✅ 62 - 136: Supported
  3. ✅ 137: Supported
  4. ✅ 138 - 140: Supported

Edge

  1. ❌ 12 - 18: Not supported
  2. ✅ 79 - 136: Supported
  3. ✅ 137: Supported

Safari

  1. ❌ 3.1 - 16.3: Not supported
  2. ✅ 16.4 - 18.4: Supported
  3. ✅ 18.5: Supported
  4. ✅ 26.0 - TP: Supported

Firefox

  1. ❌ 2 - 77: Not supported
  2. ✅ 78 - 138: Supported
  3. ✅ 139: Supported
  4. ✅ 140 - 142: Supported

Opera

  1. ❌ 9 - 48: Not supported
  2. ✅ 49 - 116: Supported
  3. ✅ 117: Supported

IE

  1. ❌ 5.5 - 10: Not supported
  2. ❌ 11: Not supported

Chrome for Android

  1. ✅ 137: Supported

Safari on iOS

  1. ❌ 3.2 - 16.3: Not supported
  2. ✅ 16.4 - 18.4: Supported
  3. ✅ 18.5: Supported
  4. ✅ 26.0: Supported

Samsung Internet

  1. ❌ 4 - 7.4: Not supported
  2. ✅ 8.2 - 27: Supported
  3. ✅ 28: Supported

Opera Mini

  1. ❌ all: Not supported

Opera Mobile

  1. ❌ 10 - 12.1: Not supported
  2. ✅ 80: Supported

UC Browser for Android

  1. ✅ 15.5: Supported

Android Browser

  1. ❌ 2.1 - 4.4.4: Not supported
  2. ✅ 137: Supported

Firefox for Android

  1. ✅ 139: Supported

QQ Browser

  1. ✅ 14.9: Supported

Baidu Browser

  1. ✅ 13.52: Supported

KaiOS Browser

  1. ❌ 2.5: Not supported
  2. ✅ 3: Supported
Resources:
Blog post on lookbehind assertions
Safari implementation bug
Firefox implementation bug
MDN: Regular Expressions Assertions