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

Zack Lee
PLUS
Zack Lee
Courses Plus Student 17,662 Points
Posted by Zack Lee
Zack Lee
Courses Plus Student 17,662 Points

why won't this work?

terribly confused as to why this statement will not work. All thats asked is to make the if statement functional.

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];

       // replace 'false' with a correct test condition on the line below
       if (law = 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>

3 Answers

William Olojede
PLUS
William Olojede
Courses Plus Student 2,752 Points
William Olojede
William Olojede
Courses Plus Student 2,752 Points

My first observation is: in the if statement you are setting law to index not comparing them, you are meant to use "==" or "===" to compare two values.

William Olojede
PLUS
William Olojede
Courses Plus Student 2,752 Points
William Olojede
William Olojede
Courses Plus Student 2,752 Points

Here is one way to do it, I explained below.

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

You got the logic wrong inside of your for loop, what you did was compare law which refers to the current element in loop with index(the user input) which is a number, both can't be equal. What you should have done is compare the current index(i) of the loop with the user input(index). Also in my opinion there's no point doing law = laws[i];.

Zack Lee
PLUS
Zack Lee
Courses Plus Student 17,662 Points
Zack Lee
Zack Lee
Courses Plus Student 17,662 Points

I actually figured it out about 5 minutes after posting the problem. My solution for the if statement was (laws[index] == law). I agree, i felt laws wasn't needed, but that was the code that was provided. All they wanted was a true if statement.