As JavaScript is case sensitive, so case-sensitive comparison are simple string comparisons. This can be done without using any JavaScript method:
<!DOCTYPE html>
<html>
<body>
<h3>JavaScript Strings</h3>
<p id="test"></p>
<script>
var str1 = "amit";
if (str1 === "amit") {
document.getElementById("test").innerHTML = "correct"
}
</script>
</body>
</html>