Here you have the prototype code of the next Terminator fan page:
<!DOCTYPE html>
<html>
<head>
<title>Terminator Fan Page</title>
</head>
<body>
<form action="/">
<input type="text" name="name"/>
<input type="submit" value="Send"/>
</form>
</body>
</html>
One of my colleagues has written the next code that will log the name we send using the form in the previous page.
<script>
function sayonara( name ) {
console.log( 'Sayonara ' + name + '!' );
}
sayonara( greetings );
</script>
But then someone sends the next message as a name and the behaviour of the page changes...
'</script><script>console.log("I will come back!")</script><script>'
Here is an example of executing the page with the bug:
<!DOCTYPE html>
<html>
<head></head>
<body>
<script>
var result = '';
function sayonara( name ) {
result = 'Sayonara ' + name + '!';
}
sayonara( '</script><script>console.log("I will come back!")</script><script>' );
</script>
</body>
</html>
Fix the code:
var result = '';
function sayonara( name ) {
result = 'Sayonara ' + name + '!';
}
sayonara( '<\/script><script>console.log("I will come back!")<\/script><script>' );
assert(result === 'Sayonara <\/script><script>console.log("I will come back!")<\/script><script>!');