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Kyle Papili
9,112 PointsWhat does the function(e) do?
I am taking this course and I have accomplished the task in this video. I am just a bit curious about what the 'e' variable does. For example:
$canvas.mousedown(function (e) { lastEvent = e; mouseDown = true;
...it appears to me that the e value represents the mouse's current location. Is that true?
4 Answers
Brigette Eckert
16,957 Pointse is short for event and can capture the event. So in this case its specifically its capturing the mousedown and only running it when the mouse is pressed down vs. up or in another direction.
Rifqi Fahmi
23,164 Pointsooooo i see because this is the anonymous function, its different with normal function such as :
function exFunct(e){
//doing something here such as
echo e;
}
with
$('canvas').mousedown(function(e){
lastEvent = e;
})
The 'e' inside that function is different meaning right? the first function e is argument, but the second anon function e is event. Am I right ?? :D
Chyno Deluxe
16,936 PointsYou are almost correct. You are correct in regards to the exFunct(e). The e in this case IS an argument and is NOT the event. However, the e in the function inside the mousedown has nothing to do with it being anonymous. You can even call exFunct to run on mousedown. but the difference is that methods like mousedown(), mouseup(), click(), hover(), etc...are events and by default carry the event as the first argument.
So by default, the argument on event methods, whatever you choose to name it, will always be the event.
I hope this helps.
Rifqi Fahmi
23,164 Pointswhat if I change the code to this
$('canvas').mousedown(function(argument){
lasEvent = argument;
})
are this still going to work ?
Chyno Deluxe
16,936 PointsYes. This will still work. The e can be named anything. It will still be the event itself. so you would still have access to all of the properties of the event such as type, target, preventDefault and many others. Demo Here
Chyno Deluxe
16,936 Pointswithout having done the course. e on events are often the event itself.
so in this case, from the looks of it, e = the mousedown event.
klick
2,170 PointsSo is āeā reserved and will always represent the (genuine) nature of the method?
Chyno Deluxe
16,936 PointsNo it is not a reserved keyword but you will commonly see e or event used in real world applications.