The read-only property returns an integer that represents the number of style declarations in this CSS declaration block.

An integer that provides the number of styles explicitly set on the parent of the instance.

The following gets the number of explicitly set styles on the following HTML element:

<div
  id="div1"
  style="margin: 0 10px; background-color: #CA1; font-family: monospace"></div>

JavaScript code:

const myDiv = document.getElementById("div1");
const divStyle = myDiv.style;
const len = divStyle.length; // 6