Question

The following program prints “Hello world” as expected

var print = function(t){
  document.write(t);
};

var printAlias = print;

printAlias("Hello world");

But when I use the same technique with document.write it does not work.

var write = document.write ;
write("Something);

Can anybody tell me what am I missing?

Answer 1

It doesn’t work because you’ve lost the context (the “this value”) within the write method of document. You can invoke write with the call method to get it back:

write.call(document, "Something");

In your first example you are simply wrapping the call to document.write in another function, but the call itself keeps the context because you invoke write as a method of document.

So you may as well stick with the usual or your wrapper function if it’s shorter code you were aiming for! Or (thanks @Esailija) you could bind the context to document at the time you create your write variable:

var write  = document.write.bind(document);