Is there a built-in JavaScript isnumeric function similar to jQuery’s isNumeric() to check if a value is a number?

General Discussions
, ,
4

In my experience working on front-end validation, especially in forms, sometimes even typeof checks aren’t enough. If you’re specifically targeting numeric strings with decimal support, a regex-based javascript isnumeric check is my go-to.

function isNumeric(value) {
  return typeof value === "string" && /^[+-]?(\d+\.?\d*|\.\d+)$/.test(value.trim());
}

This catches valid numeric strings with or without decimals, but filters out anything funky like "12a". Great when you want tight validation without bringing in any libraries.