CSS - How to get an inline property with Javascript (font-size)


This page will show you how to retrieve with Javascript an inline property value defined with the style attribute

The How to will retrieve the 20px of the font-size from the below HTML code

<p style="font-size: 20px">Foo bar</p>

Bird's-eye view solution

This howto will use the element.style object of a javascript element. This is where the inline style definition is stored.

If the property is defined in a style sheet, the property will not be present in the element.style object and will report an empty string.

How to Steps

Define a css stylesheet

We define a stylesheet to show that the value of element.style.fontSize is not defined in this case

.sheet { font-size: 15px }

Create the HTML page

  • with an inline style
<p style="font-size: 20px">A p element with the font-size defined inline</p>
  • with a class defined in the sylesheet
<p class="sheet">A p element with the font-size defined by a stylesheet</p>

Retrieve the elements with Javascript

Get all P element

allP = document.querySelectorAll("p");

Output the value of element.style.fontSize for each element

  • The first p element will have a element.style.fontSize
console.log("The first p with an inline definition has a fontSize property of "+allP.item(0).style.fontSize);
  • The second will have not
console.log("The second p with a stylesheet definition has an undefined fontSize property "+(typeof allP.item(1).style.fontSize == 'undefined'));


Discover More
CSS - font-size property

CSS font-size in CSS is a property that defines the length (size) of a font. font-size by himself is an element of typography. responsive typography The font-size uses generally a relative sizing...

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