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

General Discussions
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1

I know jQuery provides an isNumeric() method to check if a value is an integer or number. Is there something similar in pure JavaScript that I can use without relying on jQuery?

2

I’ve worked a lot with legacy codebases that still use jQuery, and this comes up often. While there isn’t a native javascript isnumeric function, you can get pretty close using coercion with isNaN() and parseFloat().

function isNumeric(value) {
  return !isNaN(value) && !isNaN(parseFloat(value));
}

This behaves much like jQuery’s isNumeric, it checks if a value can be treated as a number. Super handy when parsing user input where numbers might come in as strings.

3

Yeah, I’ve bumped into issues with loose checks before, especially when values like "123" pass, but we actually wanted real number types. If you need a stricter javascript isnumeric check, go with this instead:”*

function isNumeric(value) {
  return typeof value === "number" && Number.isFinite(value);
}

This ensures you’re only accepting proper numeric types (not numeric-looking strings). It’s perfect for avoiding sneaky type coercion bugs in stricter codebases or APIs.

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.