Well no, if you can't declare any variable without 'var', the ' dir= "data" ' line is very explicitly assignment and not a variable declaration. You can still m

Well no, if you can't declare any variable without 'var', the ' dir= "data" ' line is very explicitly assignment and not a variable declaration. You can still make the mistake but the piece of code would stand out. The problem in javascript is that "a=12" does create a new variable, even if it's a global, and that many people just go through their code declaring only globals. If you did get a syntax error everytime you did that, you'd soon have the habit of putting var in front of every new variable you declare.