How Can I Efficiently Retrieve Specific CSS Values Using JavaScript?

Retrieving CSS Values with JavaScript

While setting CSS values with JavaScript is straightforward using the style attribute, obtaining current CSS values can be more challenging. This article addresses the question of how to retrieve a specific CSS value without parsing the entire style string.

Solution: getComputedStyle()

The solution to this problem lies in the getComputedStyle() method. This method allows you to access the computed style of an element, which includes all CSS values that have been applied to the element, including both inline and inherited styles.

To use getComputedStyle(), you pass it the element you want to retrieve the style for. It returns an object that contains all the computed style properties for that element. You can then use the getPropertyValue() method of this object to retrieve the value of a specific CSS property.

Here's an example to illustrate how to retrieve the top CSS value of an image element with the ID image_1:

var element = document.getElementById('image_1'),
    style = window.getComputedStyle(element),
    top = style.getPropertyValue('top');

console.log(top);

This code will log the current top value of the image element to the console. Note that the top value is a string, so if you need to perform any calculations on it, you'll need to convert it to a number first.

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