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<!DOCTYPE html>
<html>
<body>
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<h1>JavaScript 正则表达式</h1>
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<p>检索其后有 " all" 的 "is"：</p>
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<p id="demo"></p>
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<script>
let text = "Is this all there is";
let pattern = /is(?= all)/;
let result = text.match(pattern);
​
document.getElementById("demo").innerHTML = result;
</script>
​
</body>
</html>
​