I have this regex, but it does not do what I expect:

name.replace(/sor\s*(\d )\.\s*szék/, function () {
  return arguments[1] * 1   1;
});

My string is 1. sor 1. szék. And I would expect a return 1. sor 2. szék

but the return value is: 1. 2. Why?

CodePudding user response：

You get the value 1. 2 as the pattern sor\s*(\d )\.\s*szék does not match the leading 1. so that will be untouched.

The part arguments[1] * 1 is 1, and then you add 1 to it resulting in 2.

---

If you want to use replace, you can use 3 capture groups and use those in the replacement, passing the group parameters to the callback function of replace.

The captured digits are in group 2, and to prevent concatenating 2 strings you can add a before group 2.

let name = "1. sor 1. szék";
name = name.replace(
  /(sor\s*)(\d )(\.\s*szék)/,
  (m, g1, g2, g3) => `${g1}${ g2 1}${g3}`
);
console.log(name);

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CodePudding user response：

You could simplify the regular experession and replace only the second occurence of digits with an incremented value.

const
    string = '1. sor 1. szék.',
    result = string.replace(/\d /g, (c => v => c-- ? v :  v   1)(1));

console.log(result);

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