Welcome to the Treehouse Community

Want to collaborate on code errors? Have bugs you need feedback on? Looking for an extra set of eyes on your latest project? Get support with fellow developers, designers, and programmers of all backgrounds and skill levels here with the Treehouse Community! While you're at it, check out some resources Treehouse students have shared here.

Looking to learn something new?

Treehouse offers a seven day free trial for new students. Get access to thousands of hours of content and join thousands of Treehouse students and alumni in the community today.

Start your free trial

JavaScript Regular Expressions in JavaScript Validating a Form Form Validation

Mary Pienzi
seal-mask
.a{fill-rule:evenodd;}techdegree
Mary Pienzi
Full Stack JavaScript Techdegree Student 7,036 Points
Posted by Mary Pienzi
.a{fill-rule:evenodd;}techdegree
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

app.js 
// Type inside this function
function isValidHex(text) {
 const hexRegEx =  /\#[0-9a-fA-F]{6}/i;
  alert(hexRegEx)
}

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)";
  }
});
index.html 
<!DOCTYPE html>
<html>

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

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

</html>

2 Answers

Zimri Leijen
Zimri Leijen
11,835 Points

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.

Zimri Leijen
Zimri Leijen
11,835 Points

thanks, and no problem