javascript How to trigger native click action (rep

问题:

I'm using jQuery to bind to all links on the page (I'm using the 'click' event, but have tried various combinations of 'mousedown' and 'mouseup',together with bind() and live() to no avail).

I can intercept the click no problem (with all the above methods). What I am trying to do is send some data via a GET request, and when it completes, allow the default click action to proceed.

Since I am communicating accross-domain, I must use GET rather than POST, and so cannot make a synchronous call.

Therefore I have to return 'false' from the intercepted click event, store the event for later, then manually fire it again once the communication has completed. If I return true, the communication gets cut off mid-way as the page location changes.

The problem is, I can't find a way to fire the native click event later on.

var storedEvent;
$("#wrapper a").bind('click', function(event, processed) {
    $(event.target).unbind('click'); // temporary to make code branching easier
    storedEvent = event.target;
    event.stopPropagation();

    $.ajax({
        dataType: 'jsonp',
        data: linkData,
        jsonp: 'cb',
        url: 'xxx',
        cache: false,
        complete: function(response) {
            // How do I now go back and fire the native click event here?
            $(storedEvent).click();
        }
    });
    return false;
}

I've tried using click() and trigger() where indicated, but neither worked.

I know the submission is succeeding, and the code is branching correctly -- I have debugged that far. I just don't seem to be able to replay the event.

Note that I can't do something simple, like store the href and set window.location later -- some of the links have their own onClicks set, while others have varius targets specified. I'd ideally like to just replay the event I stopped earlier.

I started off using event delegation with live() and had everything working, apart from this -- I have simplified it down to a bind() in order to simplify the problem.

回答1:

You cannot trigger a click event on an anchor and get it to follow the href cross browser.

回答2:

Up-to-date answer: yes, you can (assuming you no longer support IE8).

Use dispatchEvent() to fire a copy of the original event.

First you need an utility function to clone the event (as browsers only allow events to be dispatched once, for security reasons):

var cloneNativeMouseEvent = function (original) {
    var copy;
    try {
        copy = new MouseEvent(original.type, original);
    } catch (stupidInternetExplorer) {
        copy = document.createEvent('MouseEvent');
        copy.initMouseEvent(original.type, original.bubbles, original.cancelable, original.view,
            original.detail, original.screenX, original.screenY, original.clientX, original.clientY,
            original.ctrlKey, original.altKey, original.shiftKey, original.metaKey, original.button,
            original.relatedTarget)
    }
    return copy;
};

In your click handler store a reference to the jQuery event for later replay:

$("#wrapper a").bind('click', function (event) {
    event.preventDefault();
    storedEvent = event;
    ...
}

And finally, in the callback where you want to trigger the click again, do it as follows:

var originalEventClone = cloneNativeMouseEvent(storedEvent.originalEvent);
storedEvent.target.dispatchEvent(originalEventClone);

Please note that, in general, events created or modified by JavaScript are marked as "not trusted" by user agents so they can't trigger default actions. Luckily click events are the only exception. (1)

回答3:

It turns out redsquare is basically correct -- it doesn't work without tearing your hair out.

IE is the problem. dispatchEvent() works fine in FireFox. In IE, you can choose fireEvent to fire any associated events (but not the click), or click() (for clicks but not events), but you can't do both properly.

I got it "almost working" by temporarily changing links' hrefs and targets so that they loaded a blank page in an iframe. I then listened for iframe "load" events to determine if the link's default action had taken place. In IE I could then fire "click" if needed, or "fireEvent" otherwise, after changing the href and target back.

However, it was too much of a hack -- what if one of the links has a bound event that relied on the href attribute being there? (thickbox seemed to carry on working, but I expect it was a race condition).

In the end I didn't need to do it at all anyway ( JavaScript/jQuery: How to make sure cross-domain click tracking event succeeds before the user leaves the page? ), so I am relieved. It turns out that I had to use POST in this case.