Understanding the 'emit' functions

[kurhlaa]

Hello,

I'm trying to understand how some parts of Phaser work. But I'm confused by the emit functions.

For example arcade/world.js script at https://github.com/photonstorm/phaser/blob/master/src/physics/arcade/World.js contains:

...
this.emit('overlap', body1.gameObject, body2.gameObject, body1, body2);
...
this.emit('collide', body1.gameObject, body2.gameObject, body1, body2);
...
sprite.emit('overlap', body.gameObject, tile, body, null);
...
sprite.emit('collide', body.gameObject, tile, body, null);
...

the same in many other places in Phaser. Please explain how to find the exact JavaScript code that is executed by these emit().

 

Thanks!

[iKest]

emit is analog of dispatch signal for EventEmitter3

[samme]

EventEmitter#emit

[kurhlaa]

So far I understand, that it's possible to do something like that:

// Setup listener
a.on('overlap', func, this);

// Run related function when needed
a.emit('overlap', param1, param2);

// Function to be executed after calling 'emit'
function func(param1, param2) {
    // ...
}

is this correct? If Yes - in Phaser there must be somewhere:

world.on('overlap', ....
sprite.on('overlap', ....

but I don't see something like that. Even if I search in Phaser for a string 'overlap' - nothing is there except emit functions

[samme]

Phaser doesn't use the collide/overlap events itself, they're for you to use.

[kurhlaa]

Oh, not everything is being used by Phaser internally, got it, thanks! But in general, if I see object.emit('eventName' ... ) - I should search for object.on('eventName' ... ) and check the function inside, correct? Can I be sure that event's name won't be obfuscated or replaced by variable, so searching for 'eventName' will always give results if such listener exists?