jquery source code, classname with linefeeds?

Question

Today I looked at the source code of the jQuery function removeClass:
There is the following line:

className = (" " + elem.className + " ").replace( rclass, " " );

rclass:

rclass = /[\n\t\r]/g,

In the book "JavaScript The Definitve Guide" from David Flanagan, 6th Edition, on page 438 there are the following sentence:

..., so the HTML class attribute is available to JavaScript code using the name className. ... and the class attribute holds a space-separated list of class names.

Why the jQuery coders assume that the class names can also be separated by tabs and line feeds?

Answer 1

Lots of web "developers" know almost nothing about what they are doing and thus write crappy code containing e.g. tab- or linefeed-separated class names.

It is a common principle to "be generous when reading but strict when writing", i.e. accept things that do not really follow $standard but never create such things.