Keydown Simulation in Chrome fires normally but not the correct key

So very very close… You just needed to override the ‘which’ property. Here’s some sample code: document.addEventListener(‘keydown’, e => console.log( ‘altKey : ‘ + e.altKey + ‘\n’ + ‘charCode (Deprecated) : ‘ + e.charCode + ‘\n’ + ‘code : ‘ + e.code + ‘\n’ + ‘ctrlKey : ‘ + e.ctrlKey + ‘\n’ + ‘isComposing : … Read more

JavaScript: remove an event listener from within that listener?

You can pass the once option to have a listener act only once, then remove itself. Docs: Example: element.addEventListener(‘eventname’, (ev) => { console.log(“event is captured only once.”); // do more stuff… }, { once: true }); From the same docs link above, modern browser support is good, but is not available for Internet Explorer.

Add onclick event programmatically

But keep in mind that addEventListener is supported in IE just from version 9. To support older versions of IE you could use something like that: if (element1.addEventListener) { // all browsers except IE before version 9 element1.addEventListener(“click”, CalCal, false); } else { if (element1.attachEvent) { // IE before version 9 element1.attachEvent(“click”, CalCal); } }

HTML5 Canvas: Get Event when drawing is finished

Like almost all Javascript functions, drawImage is synchronous, i.e. it’ll only return once it has actually done what it’s supposed to do. That said, what it’s supposed to do, like most other DOM calls, is queue-up lists of things to be repainted next time the browser gets into the event loop. There’s no event you … Read more

Adding and Removing Event Listeners with parameters

This is invalid: arr[i].el.addEventListener(‘click’, do_something(arr[i])); The listener must be a function reference. When you invoke a function as an argument to addEventListener, the function’s return value will be considered the event handler. You cannot specify arguments at the time of listener assignment. A handler function will always be called with the event being passed as … Read more

How do you trigger an ‘isTrusted=true’ click event using JavaScript in a Chrome Extension?

You can inject trusted events using the debugger interface. chrome.debugger.attach(target, “1.2”, function() { chrome.debugger.sendCommand(target, “Input.dispatchMouseEvent”, arguments) })

Are JavaScript DOM event handlers called in order of registration?

This has been changed with DOM3! While the DOM level 2 events specification did state When the event reaches the target, any event listeners registered on the EventTarget are triggered. Although all EventListeners on the EventTarget are guaranteed to be triggered by any event which is received by that EventTarget, no specification is made as … Read more

Priority when more than one event handler is bound to an element via JQuery

I want to point out that the “First come, first serve” rule is not always true, it also depends on how you register a handler: Handler1 – $(document).on(‘click’, ‘a’, function….) Handler2 – $(‘a’).on(‘click’, function….) This the above example, the Handler 2 is always called before the handler1. Have a look at this fiddle:

How to implement a lock?

Lock is a questionable idea in JS which is intended to be threadless and not needing concurrency protection. You’re looking to combine calls on deferred execution. The pattern I follow for this is the use of callbacks. Something like this: var functionLock = false; var functionCallbacks = []; var lockingFunction = function (callback) { if … Read more

How to execute code before window.load and after DOM has been loaded?

Basically, you’re looking for this: document.onreadystatechange = function(e) { if (document.readyState === ‘complete’) { //dom is ready, window.onload fires later } }; window.onload = function(e) { //document.readyState will be complete, it’s one of the requirements for the window.onload event to be fired //do stuff for when everything is loaded }; see MDN for more details. … Read more