.width() not working in jQuery

I want to do something like this in JQuery

开发者_如何学Pythonif($(this).width() < 400px){
      //do something
}

But it didnt work like that....mhm how is it correct?

width() returns a plain number, and even if not your code would have an undefined symbol since 400px is not in quotes - instead use it like this:

if($(this).width() < 400){
      //do something
}