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How to emulate Event.timeStamp

Event.timeStamp

The timeStamp attribute must return the value it was initialized to. When an event is created the attribute must be initialized to the number of milliseconds that has passed since 00:00:00 UTC on 1 January 1970.

One could trap both new Event and document.createEvent to set the timeStamp accordingly but how do you intercept events created and dispatched by the browser?

One could add an event listener (capture phase) to the document that listens on "every" event type and write the timeStamp as close to the dispatch time but that would be an ugly hack.

  • Are there any better ways to emulate Event.timeStamp ?
  • Are there any potential traps with intercepting new Event / new CustomEvent and document.createEvent.
  • Are there other ways to create events programmaticly ?
  • Are there any potential issues with adding event listeners to document and manually setting timeStamp as early as possible ?
like image 998
Raynos Avatar asked Apr 01 '12 00:04

Raynos


People also ask

What is event timeStamp?

Definition and Usage The timeStamp event property returns the number of milliseconds from the document was finished loading until the specific event was created.

How do you simulate an event in JavaScript?

addEventListener("name-of-event", function(e) { console. log(e. detail); // Prints "Example of an event" }); // Create the event var event = new CustomEvent("name-of-event", { "detail": "Example of an event" }); // Dispatch/Trigger/Fire the event document. dispatchEvent(event);

How do you add a timeStamp in HTML?

Answer: Use the Date. now() Method You can simply use the JavaScript Date. now() method to generate the UTC timestamp in milliseconds (which is the number of milliseconds since midnight Jan 1, 1970).

What is timeStamp in JavaScript?

A Timestamp represents a point in time independent of any time zone or calendar, represented as seconds and fractions of seconds at nanosecond resolution in UTC Epoch time.


1 Answers

I couldn't find any place to intercept the creation of events that were generated by the browser rather than by user code. Your "ugly hack" seems to work okay though:

addEventListener("click", function (e) {
    Object.defineProperty(e, "timeStamp", {
        get: function () { return 4; }
    });
}, true);

Obviously you'd have to call addEventListener a bunch of times with whatever event names you're interested in. Note that setting the timeStamp directly has no effect, but defineProperty works. I only tested Chrome and IE9; I'm sure interop would be a mess since we're using a getter method.

like image 155
sethobrien Avatar answered Sep 28 '22 04:09

sethobrien