How to simulate a mouse click on an tag that has no href?

Question

I want to use a userscript to automatically click on a button when a page is loaded.
The target page's HTML (which I do not control) looks like this:

<a id="signInBtn" alog-alias="qb-signin-btn" class="signInBefore btn btn-24-white grid" data-disabled="false" hidefocus="hidefocus">
    <em><b>CheckIn</b></em>
</a>

It is a strange link without an href attribute. I am trying to use this code:

var btn = $("a#signInBtn");
btn.trigger("click");

But Chrome's console gives me this:

Error in event handler for (unknown):
Error: Syntax error, unrecognized expression: a[href^=/i?]

How can my userscript click this button?

`a` tag missing attribute `href` .And you can not call `.trigger("click");` because you have not define click handler for `a` tag . — Tushar Gupta - curioustushar, Nov 23 '13 at 05:38
Can you attach a useless `href` like `javascript:void(0)` to the link? Also, `"a#signInBtn"` is redundant, as IDs must be unique; just use `"#signInBtn"` instead. — Kevin Ji, Nov 23 '13 at 05:40
@TusharGupta I am not sure. I am not famliar with javascript and html. I don't know why this a tag missing href. — einverne, Nov 23 '13 at 05:41
@mc10 Sorry. I cannot find `href` in this a tag... I am confused. — einverne, Nov 23 '13 at 05:43
@einverne Read https://developer.mozilla.org/en-US/docs/Web/HTML/Element/a — Tushar Gupta - curioustushar, Nov 23 '13 at 06:02
@TusharGupta Thank you very much. I do know that `` tag should have `href` . However when I read the HTML source code. I cannot find one href. Is there any other solutions that can avoid to use href ? — einverne, Nov 23 '13 at 06:27
@TusharGupta I cannot change the HTML source code. HTML code is not written by me.. :( — einverne, Nov 23 '13 at 06:31

score 1 · Accepted Answer · edited May 23 '17 at 11:56

jQuery .trigger() is mostly only good for events set by jQuery. And, in this case, it must be called using the target page's instance of jQuery, not the userscript's. (Also, how is your script using jQuery? The wrong method can bust the page, the script, or both.)

There may be other events required and/or AJAX to contend with, we can't tell from your question. See Choosing and activating the right controls on an AJAX-driven site.

Polling for the node and triggering mouse event(s) will work in almost all cases. Here's a complete userscript to get you started:

// ==UserScript==
// @name     _Auto-click the sign-in link
// @include  http://YOUR_SERVER.COM/YOUR_PATH/*
// @grant    GM_addStyle
// ==/UserScript==

var signInTimer = setInterval ( function() {
        var signInBtn = document.querySelector ("#signInBtn");
        if (signInBtn) {
            clearInterval (signInTimer);

            var clickEvent  = document.createEvent ('MouseEvents');
            clickEvent.initEvent ('click', true, true);
            signInBtn.dispatchEvent (clickEvent);
        }
    }
    , 200
);

How to simulate a mouse click on an tag that has no href?

1 Answers1