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JavaScript DOM Scripting By Example Editing and Filtering Names Fix DOM Manipulation Code

Posted by William Vauter
William Vauter
Courses Plus Student 4,536 Points

What am I missing here?

I am stuck. Please help.

app.js 
const laws = document.getElementsByTagName('li');
const indexText = document.getElementById('boldIndex');
const button = document.getElementById('embolden');

button.addEventListener('click', (e) => {
    const index = parseInt(indexText.value, 10);

    for (let i = 0; i < laws.length; i += 1) {
       let law = laws[i];
       let lawNum = parseInt(law.value, 10);
       // replace 'false' with a correct test condition on the line below
       if (lawNum === index ) {

           law.style.fontWeight = 'bold';
       } else {
           law.style.fontWeight = 'normal';
       }
    }
});
index.html 
<!DOCTYPE html>
<html>
<head>
  <title>Newton's Laws</title>
</head>
<body>
  <h1>Newton's Laws of Motion</h1>
  <ul>
    <li>An object in motion tends to stay in motion, unless acted on by an outside force.</li>
    <li>Acceleration is dependent on the forces acting upon an object and the mass of the object.</li>
    <li>For every action, there is an equal and opposite reaction.</li>
  </ul>
  <input type="text" id="boldIndex">
  <button id="embolden">Embolden</button>
  <script src="app.js"></script>
</body>
</html>

1 Answer

gabriel ferreira
gabriel ferreira
3,110 Points
gabriel ferreira
gabriel ferreira
3,110 Points

Hi, just compare the index with the loop counter, just like that:

if (index === i) {
  law.style.fontWeight = 'bold';
} else {
  law.style.fontWeight = 'normal';
}

Your 'lawNum' variable will always return 0 because the ".value" property is not valid on <li> tag. Run a console.log in law.value and you will see that it returns NaN (that means Not a Number)