<!DOCTYPE html>
<html>
<body>
<div id="myDiv" style="text-indent:3cm;">
This is some text. This is some text. This is some text.
This is some text. This is some text. This is some text.
This is some text. This is some text. This is some text.
This is some text. This is some text. This is some text.
</div><br>
<button type="button" onclick="myFunction()">Return text indentation of div</button>
<script>
function myFunction() {
alert(document.getElementById("myDiv").style.textIndent);
}
</script>
</body>
</html>