I have what I believe is valid javascript. However I get this: SyntaxError: Unexpected token '<'. Removing any of the script blocks, or changing around the order in the 'a' string fixes the issue. Why is that?
<script>
let a = "<!-- <script>";
</script>
<script></script><!-- --><script></script>You get the same error with:
<script>
document.write('<script>alert("foo")</script>');
</script>When "parsing" the page the browser sees this as an attempt to nest a <script> block inside another one. e.g.
<script>
<script>alert("foo")</script>
</script>
The solution is to trick the browser to see something different:
<script>
document.write('<scr' + 'ipt>alert("foo")</scr' + 'ipt>');
</script>It seems like opening a <script> tag will make interpreter wait for javascript code until the last </script> is found, except if there is a second <script> opened with javascript inside of it.
Simple <script></script> will be interpreted as part of the JS code, which is invalid.
Might be related to this thread.
<script>is not legal javascript. It is a signal to HTML that what comes next is javascript.<scriptis disallowed in embedded script. What you have above is a minor variation of the very first Example in that section.