<!DOCTYPE html>
<html>
<body>
<div id="myDiv">
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.
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()">Set line height</button>
<script>
function myFunction() {
document.getElementById("myDiv").style.lineHeight = "3";
}
</script>
</body>
</html>