Tutorial

How To Bind Specific Keys to the Keyup and Keydown Events in Angular

Angular

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Introduction

When binding to either the keyup or keydown events in your Angular 2+ templates, you can specify key names. This will apply a filter to be applied to the event, so it will trigger only when specific keys are pressed.

In this article, you will learn how to use key names when listening for keyup and keydown events.

Using Key Names

First, let’s look at an example without using a key name.

Let’s say we have an <input> element for users to provide information. We want to log to the console when the user presses the ENTER key:

<input (keydown)="onKeydown($event)">

We have bound a keydown event handler that fires onKeydown():

Next, let’s write the onKeydown() function to handle pressing the ENTER key:

onKeydown(event) {
  if (event.key === "Enter") {
    console.log(event);
  }
}

A check is performed on every keydown event to determine if the event.key value is Enter. If true, we log the event to the console.

Now the same example, but with the addition of the ENTER key name to the event:

<input (keydown.enter)="onKeydown($event)">

We have bound a keydown.enter pseudo-event handler that fires onKeydown():

Next, let’s rewrite the onKeydown() function:

onKeydown(event) {
  console.log(event);
}

By relying upon Angular’s keydown.enter pseudo-event, it is no longer necessary to manually check to see if the event.key value is Enter.

Using Special Modifier Keys and Combinations

This feature works for special and modifier keys like ENTER, escape (ESC), SHIFT, ALT, TAB, BACKSPACE, and command (meta):

Key(s) Key Name
ENTER <input (keydown.enter)="...">
ESC <input (keydown.esc)="...">
ALT <input (keydown.alt)="...">
TAB <input (keydown.tab)="...">
BACKSPACE <input (keydown.backspace)="...">
CONTROL <input (keydown.control)="...">
COMMAND <input (keydown.meta)="...">

But it also works for letters, numbers, arrows, and functional keys (F1 through F12):

Key(s) Key Name
A <input (keydown.a)="...">
9 <input (keydown.9)="...">
ARROWUP <input (keydown.arrowup)="...">
F4 <input (keydown.f4)="...">

Here is a complete list of Key Values that Angular is capable of filtering.

You can also combine keys together to trigger the event only when the key combination is triggered. In the following example, the event will trigger only if the CONTROL and 1 keys are pressed at the same time:

<input (keyup.control.1)="onKeydown($event)">

Here are a few more examples to give you an idea of what’s possible:

Key(s) Key Name
SHIFT+ESC <input (keydown.shift.esc)="...">
SHIFT+ARROWDOWN <input (keydown.shift.arrowdown)="...">
SHIFT+CONTROL+Z <input (keydown.shift.control.z)="...">

Conclusion

You have learned how Angular 2+ templates support filtering key names with keyup and keydown pseudo-events.

The benefits of this approach include less repetitive manual checks for key values and handling modifier key and non-modifier key combinations.

If you’d like to learn more about Angular, check out our Angular topic page for exercises and programming projects.

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