将数据传递给 Socket.io 回调

Question

client.on('message', function(obj){});

This works fine, but I am trying to avoid nesting, so I take the callback function out like so:

client.on('message', doThis(obj));

function doThis(obj) {}

But this gives me an error saying obj is undefined.

How do I pass the message data to the callback function?

Thanks

Answer 1

client.on('message', doThis);

function doThis(obj) {}

f(doThis) is the correct syntax. f(doThis(arg)) is the wrong syntax.

The latter is calling doThis immediately with the argument arg (which doesn't exist yet).

That's why it says obj is undefined because your calling doThis immediatly.

What f(doThis) does is passes the function on instead of the return value of the function