Created
August 13, 2019 19:21
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A fix to Unhandled promise rejection error in javascript promises
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| /** | |
| * @description ### Returns Go / Lua like responses(data, err) | |
| * when used with await | |
| * | |
| * - Example response [ data, undefined ] | |
| * - Example response [ undefined, Error ] | |
| * | |
| * | |
| * When used with Promise.all([req1, req2, req3]) | |
| * - Example response [ [data1, data2, data3], undefined ] | |
| * - Example response [ undefined, Error ] | |
| * | |
| * | |
| * When used with Promise.race([req1, req2, req3]) | |
| * - Example response [ data, undefined ] | |
| * - Example response [ undefined, Error ] | |
| * | |
| * @param {Promise} promise | |
| * @returns {Promise} [ data, undefined ] | |
| * @returns {Promise} [ undefined, Error ] | |
| */ | |
| const handle = (promise) => { | |
| return promise | |
| .then(data => ([data, undefined])) | |
| .catch(error => Promise.resolve([undefined, error])); | |
| } | |
| // Explanation | |
| // The handle function takes a promise as an argument and always resolves it be returning an array with [data|undefined, Error|undefined]. | |
| // If the promise passed to the handle function resolves it returns [data, undefined]; | |
| // If it was rejected, the handle function still resolves it and returns [undefined, Error] | |
| // Usage | |
| async function userProfile() { | |
| let [user, userErr] = await handle(getUser()); | |
| if(userErr) throw Error('Could not fetch user details'); | |
| let [friendsOfUser, friendErr] = await handle( | |
| getFriendsOfUser(userId) | |
| ); | |
| if(friendErr) throw Error('Could not fetch user\'s friends'); | |
| let [posts, postErr] = await handle(getUsersPosts(userId)); | |
| if(friendErr) throw Error('Could not fetch user\'s posts'); | |
| showUserProfilePage(user, friendsOfUser, posts); | |
| } |
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