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Start your free trialHanwen Zhang
20,084 Pointswhat does the (e) in function(e) means? What does the event in function mean? do we use the (e) letter every time?
Thanks
var list = document.getElementsByTagName('ul')[0];
list.addEventListener('click', function(e) {
if (e.target.tagName == 'BUTTON') {
e.target.previousElementSibling.className = 'highlight';
}
});
<!DOCTYPE html>
<html>
<head>
<title>JavaScript and the DOM</title>
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<link rel="stylesheet" href="style.css" />
<body>
<section>
<h1>Making a Webpage Interactive</h1>
<p>Things to Learn</p>
<ul>
<li><p>Element Selection</p><button>Highlight</button></li>
<li><p>Events</p><button>Highlight</button></li>
<li><p>Event Listening</p><button>Highlight</button></li>
<li><p>DOM Traversal</p><button>Highlight</button></li>
</ul>
</section>
<script src="app.js"></script>
</body>
</html>
3 Answers
Peter Vann
36,427 PointsHi Hanwen!
The 'e' is a browser window event object that you can add event listeners to harness and corresponding code to handle/respond to (such as clicking on an element).
More info:
https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events
https://developer.mozilla.org/en-US/docs/Web/Events
https://www.smashingmagazine.com/2013/11/an-introduction-to-dom-events/
I hope that helps.
Stay safe and happy coding!
Roxanne Reyes
9,006 PointsThe 'e' means event in function, but I could be wrong.
Hanwen Zhang
20,084 PointsWhat does the event in function means? do we use the (e) letter everytime?
Peter Vann
36,427 PointsBy the way, you can actually use any variable name to reference the event object, but traditionally and logically most often 'event' or 'e' (short/abbreviation for 'event') is used.
More info:
https://developer.mozilla.org/en-US/docs/Learn/JavaScript/Building_blocks/Events
I hope that helps.
Stay safe and happy coding!
Hanwen Zhang
20,084 PointsThanks for the information!!!
Hanwen Zhang
20,084 PointsHanwen Zhang
20,084 PointsThank you Peter