Override popover option parameter with data-attributes

I'm initializing Bootstrap's popovers like this:

<!-- language: lang-js -->

$(".popovers").popover({
  placement: "right" 
});

Occasionally, I'll want to display a popover in a specific place, so I use a data-placement attribute on that particular element like this:

<!-- language: lang-html -->

<i class="popovers fa fa-question-circle"
   data-content="Some popover text." 
   data-placement="bottom" >
</i>

Bootstrap seems to ignore the data-placement attribute and uses the option settings instead.

It seems to me the data-placement attribute should override anything passed to the initialization method. I've scoured the Bootstrap 3 docs and can't find anything that confirms or denies this.

Here's a small demo:

<!-- begin snippet: js hide: true --> <!-- language: lang-js -->

$(".popovers").popover({
  container: "body", 
  trigger: "hover",
  placement: "right" 
});

<!-- language: lang-html -->

<link href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.2/css/bootstrap.css" rel="stylesheet"/>
<link href="//cdnjs.cloudflare.com/ajax/libs/font-awesome/4.3.0/css/font-awesome.css" rel="stylesheet"/>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.2/js/bootstrap.js"></script>

<div class="container">
  <i class="popovers fa fa-question-circle"
     data-content="Some popover text." 
     data-placement="bottom" 
     data-original-title="">
  </i>
</div>

<!-- end snippet -->

Is the data-placement attribute ignored when you pass in the property in JavaScript?

To answer your question:

Is the data-placement attribute ignored when you pass in the property in JavaScript?

Yes - Here's a snippet from tooltip.js:

Tooltip.prototype.getOptions = function (options) {
    options = $.extend({}, this.getDefaults(), this.$element.data(), options)

You'll see that when creating the options for each tooltip (from which popover inherits), Bootstrap calls jQuery's extend which combines the following objects in this exact order:

1. The plugin defaults
2. Then the data-attributes
3. And finally the passed in options object

Solution

To change this, we can override the GetOptions function using the Programmatic API and reversing the order of operations:

<!-- language: lang-js -->

$.fn.popover.Constructor.prototype.getOptions = function (options) {

  options = $.extend({}, this.getDefaults(), options, this.$element.data())

  if (options.delay && typeof options.delay == 'number') {
    options.delay = {
      show: options.delay,
      hide: options.delay
    }
  }

  return options
}

Additionally, we can maintain a little less code by pre-merging the options and the element data and then passing that back to the original function to override both so we don't have to spell out the entire function

<!-- language: lang-js -->

var _getOptionsOriginal = $.fn.popover.Constructor.prototype.getOptions

$.fn.popover.Constructor.prototype.getOptions = function (options) {
  options = $.extend({}, options, this.$element.data())
  return _getOptionsOriginal.call(this, options);
}

Here's a Demo in Stack Snippets:

<!-- begin snippet: js hide: true --> <!-- language: lang-js -->

var _getOptionsOriginal = $.fn.popover.Constructor.prototype.getOptions

$.fn.popover.Constructor.prototype.getOptions = function (options) {
  options = $.extend({}, options, this.$element.data())
  return _getOptionsOriginal.call(this, options);
}

$("[data-toggle='popover']").popover({placement: 'bottom'})

<!-- language: lang-html -->

<link href="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.2/css/bootstrap.css" rel="stylesheet"/>
<script src="//cdnjs.cloudflare.com/ajax/libs/jquery/2.1.3/jquery.js"></script>
<script src="//cdnjs.cloudflare.com/ajax/libs/twitter-bootstrap/3.3.2/js/bootstrap.js"></script>

<div class="container" >

  <h2>Popovers</h2>

  <button type="button" class="btn btn-default" 
          data-container="body" data-toggle="popover" 
          data-placement="right" data-content="Vivamus sagittis">
    Popover on Right - Data Attribute
  </button>
  <br/><br/>
  <button type="button" class="btn btn-default" 
          data-container="body" data-toggle="popover" 
          data-content="Vivamus sagittis">
    Popover on Bootom - Option
  </button>

</div>

<!-- end snippet -->