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JavaScript Regular Expressions in JavaScript Validating a Form Form Validation

Chelsea London
Chelsea London
Full Stack JavaScript Techdegree Student 9,378 Points

I am confused why this regular expression won't work

  • I eliminate partial matches with ^ and $
  • I include a # sign
  • I include a group of numbers and letters between a and f with [a-f0-9]
  • It needs to match 7 characters with {7}
  • I finish with the case insensitive flag i
// Type inside this function
function isValidHex(text) {
  var hexRegEx = /^#[a-f0-9]{7}$/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

Try changing 7 to 6.

While there should be a total of 7 characters, there should only be 6 repeats of [a-f0-9].