CSSStyleDeclaration.cssText

The cssText property of the CSSStyleDeclaration interface returns or sets the text of the element's inline style declaration only.

To be able to set a stylesheet rule dynamically, see Using dynamic styling information.

Not to be confused with stylesheet style-rule CSSRule.cssText.

<span id="s1" style="color: red;">
  Some text
</span>

<script>
  var elem = document.getElementById("s1");
  alert(elem.style.cssText); // "color: red;"
</script>