cannot resolve promise using fetch

Question

I cannot resolve this promise using fetch I want 2 values to go the .then(data) I want to use the status as wall as the JSON that I got form the back-end, then inherit the incoming status but the resp.json is always showing a and I cannot access its value any idea ?

fetch('/signup', { credentials: "same-origin", mode: "same-origin", method: 'POST', headers: { "Content-Type": "application/json" }, body: JSON.stringify(inputJSON) }) .then(resp => { return [resp.json(), resp.status] }) .then(function (data) { console.log(data); let Status = data[1] let jsonData = data[0] let p = jsonData.then(e => { return e }) console.log(p); }) } })

change .then(resp => { return [resp.json(), resp.status] to .then(resp => { return resp.json() and then in next .then your data will have entire resp object. Extract what you need from data — kapil pandey
– kapil pandey, Commented Jun 9, 2021 at 1:55

Gyanendro Kh · Accepted Answer · 2021-06-09 02:14:12Z

fetch('/signup', { credentials: 'same-origin', mode: 'same-origin', method: 'POST', headers: { 'Content-Type': 'application/json' }, body: JSON.stringify(inputJSON), }) .then((resp) => { return Promise.all([resp.json(), Promise.resolve(resp.status)]); }) .then(function (data) { const [json, status] = data; console.log(json); console.log(status); });

resp.json() returns a Promise, resp.status returns a Number and .then if returns a Promise will resolve it for you but if any other datatype is returned it will not do anything.

So, resp.status is converted to Promise.resolve(resp.status) to turn it into a Promise and returns Promise.all([resp.json(), Promise.resolve(resp.status)]) from .then.

Promise.all will turn multiple Promises into one.

CertainPerformance · Accepted Answer · 2021-06-09 01:54:38Z

Return a Promise.all to pass both values down the chain:

fetch('/signup', { credentials: "same-origin", mode: "same-origin", method: 'POST', headers: { "Content-Type": "application/json" }, body: JSON.stringify(inputJSON) }) .then(resp => { return Promise.all([resp.json(), resp.status]); })

Or, even better, use async/await, the control flow will be clearer:

const resp = await fetch('/signup', { credentials: "same-origin", mode: "same-origin", method: 'POST', headers: { "Content-Type": "application/json" }, body: JSON.stringify(inputJSON) }); const result = await resp.json(); // do stuff with result and with resp.status

Make sure to catch possible errors in both cases.

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