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JavaScript jQuery Basics (2014) Creating a Simple Drawing Application Perform: Part 5

Devon Handy
Devon Handy
10,000 Points
Posted by Devon Handy
Devon Handy
10,000 Points

What is the purpose of the "e" in the mousedown and mousemove functions? Is it a variable? A name? 

$canvas.mousedown(function(e){
   lastEvent = e;
   mouseDown = true;

Why does it need the "e"? Where else would I need use syntax like this? How does it work? Will I ever stop asking questions? ;)

2 Answers

Dino Paškvan
Dino Paškvan
Courses Plus Student 44,108 Points

e is the event object. When you're dealing with event handlers, you write a function that gets called every time an event is triggered (mouse movement, mouse click, key press...).

That function gets passed an event object as a parameter. You usually call it event, evt, or just e.

The event object allows you to access the event interface, to find out what type of event it was exactly, to prevent the default behavior of the event and so on.

Jason S
Jason S
16,247 Points
Jason S
Jason S
16,247 Points

I have a question about this too. What's the difference between an event and event handler and event interface , and why does mouseup not have the e? also when we write canvas.mousedown.mouseup is that the same as canvas.mousedown; canvas.mouseup?

davidschreiter
davidschreiter
15,005 Points
davidschreiter
davidschreiter
15,005 Points

It's a character from the show entourage i do believe.

Johnny Garces
Johnny Garces
Courses Plus Student 8,551 Points

funny but useless. please stick to comedy outside of this forum.

davidschreiter
davidschreiter
15,005 Points

I only have time for one chore, Tend the garden or clean the gutters. Should I choose the farmer or the ladder?

Don't rain on my parade, bro.