Created
April 20, 2015 10:40
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JavaScript regexes are stateful!
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| var youtubeRegexp = /https?:\/\/(?:[0-9A-Z-]+\.)?(?:youtu\.be\/|youtube(?:-nocookie)?\.com\S*[^\w\s-])([\w-]{11})(?=[^\w-]|$)(?![?=&+%\w.-]*(?:['][^<>]*>|<\/a>))[?=&+%\w.-]*/gi; | |
| console.log(youtubeRegexp.test("https://www.youtube.com/watch?v=o4nCcgWFEwU")); | |
| console.log(youtubeRegexp.test("https://www.youtube.com/watch?v=o4nCcgWFEwU")); | |
| console.log(youtubeRegexp.test("https://www.youtube.com/watch?v=o4nCcgWFEwU")); | |
| console.log(youtubeRegexp.test("https://www.youtube.com/watch?v=o4nCcgWFEwU")); | |
| console.log(youtubeRegexp.test("https://www.youtube.com/watch?v=o4nCcgWFEwU")); | |
| console.log(youtubeRegexp.test("https://www.youtube.com/watch?v=o4nCcgWFEwU")); | |
| // Prints true, false, true, false... |
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I didn't know this and I found a StackOverflow answer that explains why. Seems it bites a lot of people.
TL; DR: This is by design and it's in the spec.