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JavaScript Regular Expressions in JavaScript Validating a Form Form Validation

Mary Pienzi
Mary Pienzi
Full Stack JavaScript Techdegree Student 7,036 Points

Regular Expressions in JavaScript Challenge Task 1 of 2

I'm to build a literal string for the regex that fits the hexadecimal format #0000FF; so far I've got the string i want but the result is coming back stating that I need to limit the selection to fit. It's stating that it can be other values. How can it be other values when I'm telling it to be 0-9a-fA-F. /#[0-9a-fA-F]{6}/i

// Type inside this function
function isValidHex(text) {
 const hexRegEx =  /\#[0-9a-fA-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>


2 Answers

Because your regex will match strings that are longer than 6 characters.

You didn't specify that regex should start looking at the start, or that it should fail the test if the string continues after the end.

So things like wahteverrandomcharactersarehereareignored#5ef345 and #453def2 are valid.

To ensure it correctly cuts off at the beginning and end, use ^ at the start and $ at the end.

thanks, and no problem