Selecting Multiple Elements height();

Question

I am just wondering why this jQuery won't work:

hdr = $('.header-wrapper, #top-bar, #new-showroom-header').height();

So as you can see I am trying to get the height of multiple elements and store them all within my variable. I'd expect jQuery to add all of the elements heights together to create a final value however when I console.log the variable hdr I get the height of the first element selected.

Any idea how I can select all and store them into my var?

Answer 1

Use $.each() to get total sum of height.

var hdr = 0;
$('.header-wrapper, #top-bar, #new-showroom-header').each(function () {
    hdr += $(this).height();
});

FIDDLE DEMO

Answer 2

You can write a jQuery plugin for this scenario. :)

The following code below will return an array of heights based on the provided selectors.

[20,30,80]

jQuery Plugin

(function($) {
  $.fn.heights = function() {
    return this.map(function() {
    	return $(this).height();
    }).toArray();
  };
}(jQuery));

var heights = $('.header-wrapper, #top-bar, #new-showroom-header').heights();

document.body.innerHTML = JSON.stringify(heights); // [20,30,80]

body                 { font-family: monospace; white-space: pre; }
.header-wrapper      { height: 20px; }
#top-bar             { height: 30px; }
#new-showroom-header { height: 80px; }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

<div class="page-wrapper">
  <div class="header-wrapper"></div>
  <div id="top-bar"></div>
  <div id="new-showroom-header"></div>
</div>

---

Alternatively, you could build a cache of heights along with their selectors.

{
  "html>body>div>.header-wrapper": 20,
  "html>body>div>#top-bar": 30,
  "html>body>div>#new-showroom-header": 80
}

(function($) {
  $.reduce = function(arr, fn, initVal) {
    if (Array.prototype.reduce) { return Array.prototype.reduce.call(arr, fn, initVal); }
    $.each(arr, function(i, val) { initVal = fn.call(null, initVal, val, i, arr); });
    return initVal;
  };
  $.fn.heights = function() {
    return $.reduce(this, function(map, el) {
      map[$(el).fullSelector()] = $(el).height();
      return map;
    }, {});
  };
  $.fn.fullSelector = function() {
    var sel = $(this)
      .parents()
      .map(function() { return this.tagName.toLowerCase(); })
      .get()
      .reverse()
      .concat([this.nodeName])
      .join(">");
    var id = $(this).attr('id'); if (id) { sel += '#' + id; };
    var cls = $(this).attr('class'); if (cls) { sel += '.' + $.trim(cls).replace(/\s/gi, '.'); };
    return sel;
  }
}(jQuery));

var heights = $('.header-wrapper, #top-bar, #new-showroom-header').heights();

document.body.innerHTML = JSON.stringify(heights, null, 2);

body                 { font-family: monospace; white-space: pre; }
.header-wrapper      { height: 20px; }
#top-bar             { height: 30px; }
#new-showroom-header { height: 80px; }

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>

<div class="page-wrapper">
  <div class="header-wrapper"></div>
  <div id="top-bar"></div>
  <div id="new-showroom-header"></div>
</div>

Credit for the selector algorithm goes to Jesse Gavin.