Why does my jQuery click handler appear to run mul

问题:

I apply:

$(".newContentLink").click(function() {
    $("#test").append("1");
});

On this:

<span id="contents">
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
<span id="content1" class="content study">
</span>
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
<span id="content3" class="content study">
</span>
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
<span id="content4" class="content category">
</span>
<input class="newContentLink" type="submit" style="width: 100%;" value="CREATE A NEW CONTENT"/>
</span>

How come when I click on the first 2 buttons it adds 111, the next button adds 11, and the last one adds 1?

回答1:

Unable to replicate. I suspect that you're misrepresenting — oversimplifying, mostly — your situation. To be precise, I believe you're dynamically adding those inputs, and calling $(".newContentLink").click(...) each time — which, naturally, keeps applying additional copies of the click handler to each .newContentLink in the page.

So the most recent input you've created has one copy of the click handler and appends one 1. The second most recent has two copies and appends 11. The third has three and appends 111, etc.

To prevent this, apply the click handler to your newly created DOM element, not $(".newContentLink") (which always means every .newContentLink).

回答2:

or you can unbind the click event each time you add a new element

$('.newContentLink').unbind('click');

$(".newContentLink").click(function() {
    $("#test").append("1");
});

回答3:

As chaos says, you're probably calling click() each time you add one, and they're accumulating.

If you're adding these items to the document dynamically, and need to make sure this function is added to every one you add, how about using live?

$('#contents').on('click', '.newContentLink', function() {
    $("#test").append("1");
});

This will make sure the rule is dynamically applied once to any qualifying class in the document.

回答4:

Not a jQuery bug - Working Demo

There must be a problem with something else in your code. Where is the element with id="test" in your markup?

EDIT:

Just read chaos' answer, which sounds like a plausible explanation.

By the way, element ids must be unique within HTML markup - this is part of the HTML specification and may be another possible explanation

回答5:

To make sure the function only execute once on one click event you may use $(".newContentLink").one();

$(".newContentLink").one(function() {
    $("#test").append("1");
});

回答6:

Try giving different names to your submit input elements.

回答7:

I had a similar problem.... Figured out that I was applying the change function in a loop...i.e. my earlier code was....

$("table#UserIRTable > tbody > tr").each(function()
{
   ..............
   ..............

  $("input[id='thisMonthSupply']").change(function(e){  
      ......
    });
  ..........
  ..........
}

took the change function out and bingo... it worked.....