redux-thunk-recursion-detect

A drop-in replacement for redux-thunk that allows other middleware to detect that a thunk has been dispatched from within another thunk.

WTF, why would I care about this?

Ah, yes, a very good question. I wish the answer was "you don't ever have to" and this middleware didn't need to exist. However, there exist some edge cases, (error handling being one of them) where knowing that you're at the top of the redux dispatch call stack is important.

I wrote an explanation that helps understand one such case in redux-thunk-error-handler's thunkErrorHandling.md

Usage

``bash
npm install redux-thunk-recursion-detect
`

Normally, you can just replace anywhere you're using redux-thunk with this library instead.

`js
import { createStore, applyMiddleware } from 'redux';
import thunkMiddleware from 'redux-thunk-recursion-detect';

const store = createStore(myReducerFn, applyMiddleware(thunkMiddleware));
`

Then, in some other middleware that needs to know whether or not a thunk was dispatched from inside another thunk, you can use the isNestedThunkSymbol export to test for it.

`js
import { isNestedThunkSymbol } from 'redux-thunk-recursion-detect';

export const myCoolMiddleware = store => next => action => {
if (typeof action === 'function' && action[isNestedThunkSymbol]) {
// The thunk that is currently in the dispatch pipeline is a nested thunk.
doWhateverINeedForNestedThunks();
return next(action);
} else {
// The thunk is at the top level of its call stack
return next(action)
}
}
``

Take a look at redux-thunk-error-handler to see a real application of this middleware.

A part of the thunk-centric-redux set of tools

This library is part of a larger set of tools that can be helpful for making thunk-centric Redux applications. Visit that project to see a runnable example app that makes use of this code in context.

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Copyright (c) 2015-2018 Ian Taylor

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