Created
April 29, 2020 10:28
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A function for simulating key event in JavaScript. You just have to choose what key and keyboard event you want to simulate.
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/** | |
* Simulate a key event. | |
* @param {Number} keyCode The keyCode of the key to simulate | |
* @param {String} type (optional) The type of event : down, up or press. The default is down | |
* @param {Object} modifiers (optional) An object which contains modifiers keys { ctrlKey: true, altKey: false, ...} | |
*/ | |
function simulateKey (keyCode, type, modifiers) { | |
var evtName = (typeof(type) === "string") ? "key" + type : "keydown"; | |
var modifier = (typeof(modifiers) === "object") ? modifier : {}; | |
var event = document.createEvent("HTMLEvents"); | |
event.initEvent(evtName, true, false); | |
event.keyCode = keyCode; | |
for (var i in modifiers) { | |
event[i] = modifiers[i]; | |
} | |
document.dispatchEvent(event); | |
} | |
// Setup some tests | |
var onKeyEvent = function (event) { | |
var state = "pressed"; | |
if (event.type !== "keypress") { | |
state = event.type.replace("key", ""); | |
} | |
console.log("Key with keyCode " + event.keyCode + " is " + state); | |
}; | |
document.addEventListener("keypress", onKeyEvent, false); | |
document.addEventListener("keydown", onKeyEvent, false); | |
document.addEventListener("keyup", onKeyEvent, false); | |
// Using the function | |
simulateKey(38); | |
simulateKey(38, "up"); | |
simulateKey(45, "press"); |
Also not working for me on Chrome Version 109.0.5414.120
some improvements and applied the function to typescript.
simulateKey(keyCode: number, type: string, modifiers: {[key: string]: any} = {'isTrusted': true}): void {
const evtName = (typeof type === 'string') ? 'key' + type : 'keydown';
const modifiersObj = (modifiers instanceof Object) ? modifiers : {};
const event = new KeyboardEvent(evtName, { keyCode });
Object.assign(event, modifiersObj);
document.dispatchEvent(event);
}
what to call
simulateKey(38);
simulateKey(38, "up");
simulateKey(45, "press");
Tested on Chrome ( Version 110.0.5481.77 (Official Version) 64-bit)
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This doesn't work for me, on Chrome 109. What could be the reason? Any help with diagnosing the issue would be appreciated. Thanks!