node js buffer and var difference
while using Node js if I use
buf1= new Buffer(50); and var buf='';
It seems like you are rather confused about this, or just worded this question in a strange manner. In my experience, it's pretty rare that you'll want to use a buffer over something like a string unless you are dealing with streaming or low-level operations. It seems like the first variable you declared is a buffer, and the second one is a string. If you add a little more context, I'd be able to help you decide whether you need a buffer or a string.
In general, I think the docs on Buffer are what you're after: http://nodejs.org/api/buffer.html#buffer_buffer