foo in bar - 'in' operator javascript?

Question

I recently read a tutorial on CSS browser feature detection... The end product was something like this...

var prefix = [\'Moz\', \'webkit\', \'O\', \'ms\', \'Kht         


        

Answer 1

if (foo in bar) is used to check whether the value named foo is a property of the object bar. Since arrays are just specially treated objects, you are correct in assuming that it can be used to check for a value in an array.

test_style = document.createElement('div').style returns an object with properties; since this is the case, you can use the foo in bar syntax to check it.