<!DOCTYPE html>
<html>
<body>
<p>Click the button, and display "green" if a boolean value is <em>true</em>, otherwise display "red".</p>
<button onclick="myFunction()">Try it</button>
<p id="demo"></p>
<script>
Boolean.prototype.myColor = function() {
if (this.valueOf() == true) {
return "green";
} else {
return "red";
}
};
function myFunction() {
var a = true;
document.getElementById("demo").innerHTML = a.myColor();
}
</script>
</body>
</html>