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JSの正規表現の先読み後読み

Last updated at Posted at 2020-02-21

肯定先読み

> /a(?=b)/.test("ab")
true

否定先読み

> /a(?!b)/.test("ab")
false

肯定後読み

> /(?<=a)b/.test("ab")
true

否定後読み

> /(?<!a)b/.test("ab")
false
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