What is passed to the function in a Promise .catch block?

Question

What's the general difference between these two styles of handling .catch blocks in Promises:

...
.catch(e => myMethod(e))

...
.catch(myMethod)

What does a Promise's .catch pass to the received method?

eg Can there be additional arguments?

Answer 1

In both cases, there is only one argument.

There's no fundamental difference between these two styles, except that an arrow function behaves differently than a real function , especially this will be undefined or window (depending on whether strict mode is enabled or not) with a function , and with an arrow function it's the same this as the context in which it is declared.

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From this MDN Catch Syntax documentation :

This .catch has one argument: reason : The rejection reason.

From this MDN Arrow Function documentation :

An arrow function expression is a syntactically compact alternative to a regular function expression, although without its own bindings to the this, arguments, super, or new.target keywords . Arrow function expressions are ill suited as methods, and they cannot be used as constructors.

Answer 2

In catch(e => myMethod(e)) , you are passing an anonymous function which takes a parameter e and calls myMethod(e)

In catch(myMethod) , you are directly passing your myMethod instead of that anonymous function (in above case), which takes a parameter e .

So, both are same. And the parameter passed e is the "reason" for being rejected.