Chained Arrow function syntax

Question

const fetch = url => dispatch => {
  // ...
}

export const fetchQuestions = tag => (dispatch) => {
  return dispatch(fetch(tag));
};

What

Answer 1

Its a shorter way of writing a function that returns another function. The arguments url and dispatch are arguments to the curryed function The ES5 equivalent of arrow function syntax would be

function fetch(url) {
    return function(dispatch) {
         ....
    }
}

or with Arrow syntax as

const fetch = (url) => {
    return (dispatch) => {
        // ... 
    }
}

Similarly you would have fetchQuestion written as

export function fetchQuestions(tag) {
     return function(dispatch){
            return dispatch(fetch(tag));
     }
}

or with Arrow syntax as

export const fetchQuestions = (tag) => {
    return (dispatch) =>  {
        return dispatch(fetch(tag));
    }
};