Geek asks and answers

Why if (true && false); {foo (); } valid?

This is one unpleasant mistake that took me half an hour. The compiler considers this to be valid code, and when it evaluates the statement, it still calls foo ():

if(true && false);{ foo(); }

Why is this really and why is foo () still being called?

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8 answers

Well, you didn’t ask a question, but I feel obligated to tell you why the compiler is right and the code is valid (sorry, SO people):

if (true && false);

This is just an empty statement that is executed if the condition is met (in this case, it is not fulfilled due to && false, therefore, nothing happens (but nothing happens in any case)). The statement is empty because the closing bracket is immediately followed by a semicolon.

{ foo(); }

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, , : jslint, .

For example, here is the javascript buffer in emacs, flymake-for-javascript - emacs' on-the-fly validation syntax - included:

enter image description here

(ps: this image also uses flymake-cursor.el to automatically display the error message below)

JSLint can be run from the command line, it can be included in the automatic build process, or it can be integrated into a development tool. If you have not verified this, do so. You will learn some good Javascript coding habits.

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