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JavaScript JavaScript and the DOM (Retiring) Making Changes to the DOM Appending Nodes

Luis Diaz
.a{fill-rule:evenodd;}techdegree seal-36
Luis Diaz
Front End Web Development Techdegree Graduate 13,943 Points

Getting UnUncaught TypeError: Cannot read property 'addEventListener' of null

Hey guys although I've checked for any typos in my code I keep getting this is error in the console. I could use a fresh set of eyes to look over it. Thanks!

const toggleList = document.getElementById('toggleList'); const listDiv = document.querySelector('.list'); const descriptionInput = document.querySelector('input.description'); const descriptionP = document.querySelector('p.description'); const descriptionButton = document.querySelector('button.description'); const addItemInput = document.querySelector('input.addItemInput'); const addItemButton = document.querySelector('button.addItemButton');

toggleList.addEventListener('click', () => { if ( listDiv.style.display == 'none' ) { toggleList.textContent = 'Hide list'; listDiv.style.display = 'block'; } else { toggleList.textContent = 'Show list'; listDiv.style.display = 'none'; } });

descriptionButton.addEventListener('click', () => { descriptionP.innerHTML = descriptionInput.value + ':'; });

addItemButton.addEventListener('click', () => { let ul = document.getElementsByTagNameName('ul')[0]; let li = document.createElement(li); li.textContent = addItemInput.value; ul.appendChild('li'); });

<!DOCTYPE html> <html> <head> <title>JavaScript and the DOM</title> <link rel="stylesheet" href="css/style.css"> </head> <body> <h1 id="myHeading">JavaScript and the DOM</h1> <p>Making a web page interactive</p> <button id="toggleList">Hide List</button> <div class="list"> <p class="description">Things that are purple:</p> <input type="text" class="description"> <button class"description">Change list description</button> <ul> <li>grapes</li> <li>amethyst</li> <li>lavender</li> <li>plums</li> </ul> <input type="text" class="addItemInput"> <button class"addItemButton">Add Item</button> </div> <script src="app.js"></script> </body> </html>

1 Answer

Armin Kadic
Armin Kadic
16,242 Points

You have 2 syntax errors in your html, one is "<button class"description">Change list description.</button>" - you forgot to put the = sign after class. The other one is "<button class"addItemButton">Add Item</button>" - same problem.

You can check your html code in the future at https://validator.w3.org/#validate_by_input

Hope this helps!