How to limit the number of multiple characters in an input value？

Question

I want to limit the number of letters at the beginning and end of the input value (e.g. QQ23F and SG21G) through JavaScript but I found that only one {} can be written in a pattern. Thanks for any help. Here is my incorrect code:

var isValid = true;
  var id=document.getElementById("pid").value;
  if (!id.match(/[A-Za-z]{2}+[0-9]+[A-Za-z]{1}/)) {
      document.getElementById("pidMessage").innerHTML="Your pid format is invalid!";
      isValid = false;
  }

{2}+ is invalid; did you mean perhaps {2,} (for 2 or more)? — Nick
– Nick, Commented Aug 24, 2022 at 13:20
Hi Nick, I just want to have 2 letters only at the starting. — Ryan Yan
– Ryan Yan, Commented Aug 24, 2022 at 13:24

Mohamed Abdallah · Accepted Answer · 2022-08-24 13:35:12Z

1

You need to add the begging ^ and end $ signs

  let isValid = true;
  let id=document.getElementById("pid").value;
  if (!id.match(/^([A-Za-z]{2}[0-9]+[A-Za-z]{1})$/)) {
      document.getElementById("pidMessage").innerHTML="Your pid format is invalid!";
      isValid = false;
  }

And for everyone's sake use let not var

edited Aug 24, 2022 at 13:35

answered Aug 24, 2022 at 13:19

Mohamed Abdallah

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3 Comments

Ryan Yan Over a year ago

Hi, thanks for your help. I tried this again but the console still says Uncaught SyntaxError: Invalid regular expression

Mohamed Abdallah Over a year ago

@RyanYan, I updated my code. Please check.

Mohamed Abdallah Over a year ago

@RyanYan, Glad to hear that. Please mark that as the answer to the question.

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