Getting an element's inner height

dom, javascript

Solution

clientHeight - give the height including padding but without the borders.

getComputedStyle - a way to tap into the CSS rules of an element and retrieve a property's value (padding)

Using parseInt is a way to strip away units and leave only the numeric value (which is in pixels) `parseFloat` can also be used for more precise sub-pixel measurements

Note that all values will automatically be converted by the DOM API to pixels

function getInnerHeight( elm ){
  var computed = getComputedStyle(elm),
      padding = parseInt(computed.paddingTop) + parseInt(computed.paddingBottom);

  return elm.clientHeight - padding
}

DEMO:

// main method
function getInnerHeight( elm ){
  var computed = getComputedStyle(elm),
      padding = parseInt(computed.paddingTop) + parseInt(computed.paddingBottom);
  
  return elm.clientHeight - padding
}

// demo utility function
function printInnerHeight( selector ){
  console.clear()
  console.log(
    getInnerHeight( document.querySelector(selector) )
  )
}

body{ display: flex; padding:0; margin: 0; }
div{ flex: 1; }

.demo1{
  padding-top: 2vh;
  padding-bottom: 1vh;
  margin: 30px;
  border: 10px solid salmon;
  box-sizing: border-box;
  outline: 1px solid red;
}

.demo2{
  padding-top: 2vh;
  padding-bottom: 4vh;
  margin: 30px;
  border: 10px solid salmon;
  border-bottom-width: 0;
  height: 150px;
  outline: 1px solid red;
}


p::before{
  content: '';
  display: block;
  height: 100%;
  min-height: 50px;
  background: lightgreen;
}

<div>
  <h2>inner height should be ~50px</h2>
  <button onclick="printInnerHeight('.demo1')">Get Inner Height</button>
  <p class='demo1'></p>
</div>
<div>
  <h2>inner height should be ~150px</h2>
  <button onclick="printInnerHeight('.demo2')">Get Inner Height</button>
  <p class='demo2'></p>
</div>

Problem

How do you get an element's inner height, without padding and borders? No jQuery, just pure JS, and a cross-browser solution (IE7 included)

Original source

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