Why is the script tag broken up in to two strings? [duplicate]

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Closed 8 years ago.

Possible Duplicate:
Why split the <script> tag when writing it with document.write()?

Looking at the enyo source, I see this (in enyo.js):

document.write('<scri' + 'pt src="' + root + "/source/boot/" + inSrc + '"></scri' + 'pt>');

Why is the <script tag broken into <scri + pt ? The same is done for the end tag. Is this a secret of the Javascript ninja that I'm not aware of?

Answer 1

When a browser's html parser sees the string "</script>", regardless of whether it is in a javascript string or not, it sees it as a closing script tag and ends the current script block. Breaking the "</script>" tag into two pieces prevents this from happening when you need it as a javascript string.

See this explanation:

the tag is content-agnostic. Which means the HTML Parser doesn’t know we’re in the middle of a JavaScript string.

The processing of JavaScript doesn’t happen until after the browser has understood which parts are JavaScript. Until it sees that close tag, it doesn’t care what’s inside – quoted or not.

Answer 2

it is designed to get the script tag around various filters.

Answer 3

To prevent browsers from blocking the document.write. It's usually unsafe to do things of this sort.

Also, for old browsers which when seeing </script> anywhere in the body, would stop execution right away. Which meant anything after the document.write wouldn't be considered JavaScript code.

See this fiddle to see what I mean. The script tag closes right after the alert.

Answer 4

This is necessary because the parser considers that substring as the closing <script> tag in which the statement itself is contained, so it's necessary make a split somewhere in the middle