How Can I Accurately Determine the Font Size of an HTML Element?

Determining Font Size in HTML

Determining the font size of a text element is a common task in web development. However, relying solely on the 'style.fontSize' property may not suffice in all cases.

Issue and Context

In the example provided, 'style.fontSize' fails to provide the desired result when retrieving the font size value. This is because the font size may be inherited from a stylesheet, resulting in an empty string ('') value.

Solution: Using 'window.getComputedStyle()'

To accurately obtain the font size, utilize the 'window.getComputedStyle()' method. This method provides computed values for the element's style, including inherited properties.

Here's an updated example:

var el = document.getElementById('foo');
var style = window.getComputedStyle(el, null).getPropertyValue('font-size');
var fontSize = parseFloat(style); // Convert to a float
el.style.fontSize = (fontSize + 1) + 'px'; // Add 1 to the size and set it with units

Using 'window.getComputedStyle()', you obtain the true computed font size as a float value. This allows for precise font size manipulation, addressing the limitations of 'style.fontSize' for inherited properties.

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