Fetch API not giving response data in Node.js - node.js

Question

I have been trying to fix this but it gives me this: ReferenceError: json is not defined
this is my code:
const fetch = require('node-fetch');
function makeAFile(text){
fetch("http://bin.shortbin.eu:8080/documents", {
method: "post",
body: 'hey wassup'
})
.then(res => res.json())
.then(json => console.log(json))
.catch(err => console.log(err))
return json
}
console.log(makeAFile('nope'))

Answer 1

You need to understand, how async call works.
const fetch = require('node-fetch');
function makeAFile(text){
fetch("http://bin.shortbin.eu:8080/documents", { // this is async call
method: "post", // might give result later in time
body: 'hey wassup'
})
.then(res => res.json())
.then(json => console.log(json))
.catch(err => console.log(err))
return json // JSON is not defined and will be return just after 'Fetch' is called which is 'undefined'
console.log(makeAFile('nope'));
To make your code sync, you should use async await like this:
const fetch = require('node-fetch');
async function makeAFile(text){
let res = await fetch("http://bin.shortbin.eu:8080/documents", { // await helps you to wait here to make your code sync
method: "post",
body: 'hey wassup'
})
const json = res.json()
return json ;
}
try {
const response = await makeAFile('nope')); //use try catch to catch error
console.log(response);
}
catch (error) {
console.log(`Error ${error}`);
}

Answer 2

You seem to be confused with how to return data from an async call. You do that using callbacks like this:
const fetch = require('node-fetch');
function makeAFile(text){
return fetch("http://bin.shortbin.eu:8080/documents", {
method: "post",
body: text
})
.then(res => res.json())
.catch(err => { console.error(err) })
}
makeAFile('nope').then((result) => console.log(result));
You can read more about it here;
EDIT: Provide a solution using async/await
async function makeAFile (text) {
try {
const res = await fetch("http://bin.shortbin.eu:8080/documents", {
method: "post",
body: text
})
return res.json();
} catch (err) {
console.error(err);
}
}
// Define an anonymous async function to allow await statements inside
(async () => {
// this "await" here is important
const result = await makeAFile('nope');
console.log(result);
// now result is store inside of "result"
})();

Answer 3

You don't have access to json outside then callback. Just make your function async, that way you will have an access to it and outer context code can wait till your function will be resolved or rejected:
const fetch = require('node-fetch');
async function makeAFile(text){
const res = await fetch("http://bin.shortbin.eu:8080/documents", {
method: "post",
body: 'hey wassup'
})
const json = res.json()
console.log(json)
return json
}
and call it like:
try {
const result = await makeAFile('nope')
console.log(result)
} catch(err) {
console.log(err)
}
or
const result = makeAFile('nope').then(result => {
console.log(result)
})
.catch(err => {
console.log(err)
});

Answer 4

const fetch = require('node-fetch');
function makeAFile(text){
jsonOut = ''
fetch("http://bin.shortbin.eu:8080/documents", {
method: "post",
body: 'hey wassup'
})
.then(res => res.json())
.then(json => jsonOut = json)
.catch(err => console.log(err))
return jsonOut
}
console.log(makeAFile('nope'))
you cannot access value inside a promise. Just check this code