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JavaScript 正则表达式后向断言 (?<=y)x
tryjsref_regexp_lookbehind
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<!DOCTYPE html> <html> <body> <h1>Regular Expressions</h1> <h2>Lookbehind Assertion</h2> <p>Match "FreeW3C" only if "FreeW3C" is preceded by "Hello ".</p> <p id="demo"></p> <script> let text = "Hello FreeW3C"; let pattern = /(?<=Hello )FreeW3C/; let result = pattern.test(text); document.getElementById("demo").innerHTML = result; </script> </body> </html>