Dispatch key events to fill an input field

[Ben Bracha]

Hi,

I'm trying to automate input-filling by dispatching key events using the CDP.

Subscribing to DOM events, I see the events being fired with "trusted:true", but the input field on the page remains empty.

Here are the commands I send, where sendCommandPromise is just a simple promise wrapper around chrome.debugger.sendCommand

await sendCommandPromise(customerTabId, 'Input.dispatchKeyEvent', {

type: 'keyDown',

key: 'a',

code: 'KeyA',

});

await sendCommandPromise(customerTabId, 'Input.dispatchKeyEvent', {

type: 'keyUp',

key: 'a',

code: 'KeyA',

});

What am I missing here?

[Ophir Back]

In JavaScript in general, the event that triggers the actual writing of the text into an input / textarea (and other) element is the event with the `KeyPress`  type.

Likewise, in CDP, the event that is required to trigger the actual writing is the `char` one. You need to have `keyUp` -> `char` -> `keyDown`.

Also, there's the `text` field in the parameters of `Input.dispatchKeyEvent` that should be filled for the `char` event (and only in this event). 

Overall, here's the type, text, key and code of writing down the letter "a" successfully with CDP:

"keyDown", undefined, "a", "KeyA"

"char", "a", "a" , "KeyA"

"keyUp", undefined, "a", "KeyA"

I hope it makes sense. If you have any questions, please let me know. 

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[Ben Bracha]

This seems to work. Thanks!

[Ben Bracha]

Actually it seems to work when sending only the "char" event, no need for the keyup/keydown

[Ophir Back]

Yeah, the "char" event is the one that triggers writing the character.

However, since in some cases there might be event listeners in place (that can also expect "keyDown" / "keyUp"), it's better to also send them.

[Ben Bracha]

Got it. Ok, thanks Ophir