Sizzle fails due to untrimmed whitespace

[NiX]

Code below will fail due to white space in the beginning of the string:

$("\n<div/>");

Same goes for \t and \r. That's all I tried so far.

My original code had a multiline string with HTML code but the example above is essentially the same thing.

It looks like this bug was introduced in 1.9.0

I tracked it down to the regex in rquickExpr

In 1.8.3 it was

rquickExpr = /^(?:[^#<]*(<[\w\W]+>)[^>]*$|#([\w\-]*)$)/,

and in 1.9.0 it became

rquickExpr = /^(?:(<[\w\W]+>)[^>]*|#([\w-]*))$/

[dmethvin]

Duplicate of #13223.
The jQuery Migrate plugin should have warned you about this, were you using it?

​https://github.com/jquery/jquery-migrate/blob/master/warnings.md#jqmigrate-html-html-strings-must-start-with--character