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JavaScript Regular Expressions in JavaScript Validating a Form Form Validation

What is wrong with this reg ex?

It works in a regex tester but the challenge says it matches non-hexadecimal values too.

// Type inside this function
function isValidHex(text) {
  const hexRegEx= /#(\d|[a-f]){6}/i;

const hex = document.getElementById("hex");
const body = document.getElementsByTagName("body")[0];

hex.addEventListener("input", e => {
  const text = e.target.value;
  const valid = isValidHex(text);
  if (valid) {
    body.style.backgroundColor = "rgb(176, 208, 168)";
  } else {
    body.style.backgroundColor = "rgb(189, 86, 86)";
<!DOCTYPE html>

    <title>DOM Manipulation</title>
<link rel="stylesheet" href="style.css" />

    <div id="content">
        <p>Enter a valid hex value below to make the screen turn green.</p>
        <input type="text" id="hex">
    <script src="app.js"></script>


1 Answer

Steven Parker
Steven Parker
216,705 Points

You're close, but the regex needs to be "anchored" to the beginning and end of the string:

  const hexRegEx = /^#(\d|[a-f]){6}$/i;

Also, it's a bit more conventional to include the digits in the character class ("[0-9a-f]"), and then the grouping and branching isn't needed.