99. Using HostListener to Listen to Host Events

Jul 15, 2026 01:03 · 3:00 · English · Whisper Turbo · 2 ลำโพง

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So we saw two examples for directives now and the better approach definitely

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

is a good approach,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

but it's not very interactive,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

right?

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

It always gives us a blue background.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And I want to change this.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

I only want to style this blue or give this a blue background if I hover

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S… Speaker 2 (99. Using HostListener to Listen to Host Events)

over it.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And if I move my mouse away,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

it should go back to transparent.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So let's improve the better highlight here a bit.

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We need to react to some events occurring on the element the

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directive sits on.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And a quick and easy way to do this inside of this directive is to

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

simply add a new decorator.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And this is the host listener decorator,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

which needs to be imported from at Angular core and added to

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

some method we want to execute.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So the method here could be mouse over.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

Now I will move this from

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

the top of the file below ng on init here.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So now this can be triggered whenever some

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

event occurs and that event is specified here as an argument as

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a string.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

Host listener here takes the argument name as an input and

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

that would be mouse enter,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

let's say.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

That is one of the events supported by

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

the DOM element this directive sits on.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So you have basically all events available you could also use with event binding

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

before.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So that's my host listener targeting this event.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And we could also receive the event data here.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So event data of type event would be passed to us here.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So that works.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

You can also listen to custom events here and retrieve that data.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So this is just like the method you execute when you add a click

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

listener or whatever your event is and then pass the method between

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

the quotation marks.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So that's happening here.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

Host listener is just a convenient way.

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of listening to events on that element.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So with that,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

we listen to the mouse entry event,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

we get the event data,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

which I don't need here.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

But what I want to do in this case is,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

I want to change the background color of the element.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So what I can do is,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

I can copy this code from Angie on init and comment it out.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And now set the style here on mouse enter.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And now I can quickly copy this and add another method.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

which I'll name mouse leave maybe,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

where I will listen to the mouse leave event,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

another official event I can listen to.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And then I want to set the background color to transparent

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

maybe.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

Now with this in place,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

we should have a reactive directive.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So now no background color.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

And if I hover over it,

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

It gets blue.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

So that is working as intended.

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S… Speaker 1 (99. Using HostListener to Listen to Host Events)

Now with host listener reacting to user event or

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to any events.

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