正则表达式分组步骤说明

Question

let quotedText = /'([^']*)'/;
console.log(quotedText.exec("she said 'hello'"));
//["'hello'", "hello"]

why does hello appear twice?

Answer 1

结果中的第一个元素是完全匹配，第二个元素是 first captured group。去掉括号 () 只得到一个结果。

let quotedText = /'[^']*'/;
console.log(quotedText.exec("she said 'hello'"));

如果你还想保留括号，可以使用如下所示的非捕获组：

let quotedText = /'(?:[^']*)'/;
console.log(quotedText.exec("she said 'hello'"));