当正则表达式有效并在其他地方工作时，带有“ m”标志的JavaScript正则表达式错误，“无效的正则表达式组”

Question

This line of regex is breaking in javascipt, however when using a regex tester it works correctly:

var pattern = new RegExp(/^(?m)^([A-Z0-9]{2,4})(?:\s*[A-Z0-9]{3})?$/);
"SL44BZ".match(pattern);

How do I make this work with javascript's .match()?

It should return an array of two results splitting at the 'SL4'.

It looks like this issue is with the multiline '(?m)' flag, however if I remove this wrong results are returned.

Answer 1

var pattern = /^([A-Z0-9]{2,4})(?:\\s*[A-Z0-9]{3})?$/m; "SL44BZ".match(pattern);

如果您还没有从评论中找出答案，则应该这样做。