When PHP is building HTML document, I add to it a code var myVariable = 'somedata';, which is used by a .js file. Of course, that file's code must be prepared for that variable not being set.
Doing some tests, I see that if I don't set the variable in HTML, Firebug console reports myVariable is not defined, and the code breaks: everything that should be run after the call to the function that uses that variable, doesn't run at all.
Only that function requires that variable, so I want the it to nicely return instead of breaking, so I used if(undefined === myVariable) return;, but it didn't work. Console still reports that error, and JS still breaks.
What's the best practice for testing if a variable is defined before using it?
