Deprecationwarning: calling an asynchronous function without callback is deprecated.

Question

Problem :

I have recently updated the node to 7.2.1 and noticed that there is the warning coming as below :

(node:4346) DeprecationWarning: Calling an asynchronous function without callback is deprecated.

Why is this 4346 ? I only have 2000 lines of code in the js file, so it must not be the line-number. Where should I look for that code?

Answer 1

I had also got the same warning

[DEP0013] DeprecationWarning: Calling an asynchronous function without callback is deprecated. 

I saw this statement-suspect:

Fs . writeFile (path, aString, cb, encoding);

So the problem was the cb (= 'callback') and the encoding arguments are in the wrong order. So I got rid of the warning simply by changing the above to below:

Fs . writeFile (path, aString, encoding,  cb);

But the problem is really with the ERRONEOUS warning-message So if the warning had informed as below

"WWARNING: calling fs.writeFile() with a string-argument 

where a function is expected"

So the point here was I was NOT calling the writeFile() without the callback-argument, which is shown as deprecated. I was trying to call the writeFile() WITH A WRONG TYPE OF ARGUMENT. So that must be an ERROR and not the warning.

I hope it solved your issue.