completed course code

Author: mtanzim

04_apiExample.js

@@ -30,7 +30,7 @@ function fetchWithCallback(callback) {
 
 const callback = function () {
   console.log('\nData fetch was completed with the https module!\n');
-}
+};
 
 Number(process.argv[2]) === 1 ?
   fetchData() :

06_promises.js

@@ -0,0 +1,62 @@
+function firstPromise (shouldFail = false, delay=1000, id=0) {
+  console.log(`The promise with id:${id} is pending...`);
+  return new Promise(function (resolve, reject) {
+    setTimeout( function () {
+      if (shouldFail) {
+        return reject(new Error(`The promise with id:${id} has failed XD XD XD`));
+      } else {
+        return resolve(`The promise with id:${id} was fulfilled!`);
+      }
+    }, delay);
+  });
+}
+
+function main() {
+
+  
+  let shouldFail = Boolean(process.argv[2]);
+  let shouldFailAll = Boolean(process.argv[3]);
+
+
+  
+  firstPromise(shouldFail)
+    .then (function (res) {
+      console.log(res);
+    })
+    .catch(function (err) {
+      console.log(err.message);
+    });
+  
+  
+  let promiseArr = [];
+  for (let i=1; i < 6; i ++) {
+    let shouldFail = false;
+    if (i % 2 === 0) {
+      shouldFail = shouldFailAll;
+    }
+    promiseArr.push(firstPromise(shouldFail, i * 1000, i));
+  }
+  
+  Promise.all(promiseArr)
+  .then (function (res) {
+    console.log('All promises were resolved:');
+    console.log(res);
+  })
+  .catch (function (err) {
+    console.log(err);
+  });
+  
+  
+  Promise.race(promiseArr)
+  .then(function (res) {
+    console.log('The following promise won the race *CLAP CLAP*');
+    console.log(res);
+  })
+  .catch(function (err) {
+    console.log('The following promise runined everything *CRY*');
+    console.log(err);
+  });
+
+}
+
+main();

07_chainedPromise.js

@@ -0,0 +1,25 @@
+new Promise(function (resolve, reject) {
+
+  setTimeout(() => resolve(1), 1000);
+
+}).then(function (result) {
+
+  console.log(result); // 1
+
+  return new Promise((resolve, reject) => { // (*)
+    setTimeout(() => resolve(result * 2), 1000);
+  });
+
+}).then(function (result) { // (**)
+
+  console.log(result); // 2
+
+  return new Promise((resolve, reject) => {
+    setTimeout(() => resolve(result * 2), 1000);
+  });
+
+}).then(function (result) {
+
+  console.log(result); // 4
+
+});

08_chainedPromiseApi.js

@@ -0,0 +1,5 @@
+const fetchData = require('./fetchData');
+
+fetchData(true);
+
+

09_asyncAwait.js

@@ -0,0 +1,19 @@
+const fetchData = require('./fetchData');
+
+async function callFetch() {
+  console.log('Calling fetch...');
+  let comments = null;
+  try {
+    comments = await fetchData(false);
+  } catch( err) {
+    console.log(err);
+  }
+
+  if (comments) {
+    comments.forEach((comment, i) => {
+      console.log(`\n${i}: ${comment.body}`);
+    });
+  }
+}
+
+callFetch();

fetchData.js

@@ -0,0 +1,32 @@
+const fetch = require('node-fetch');
+const urlUsers = 'https://jsonplaceholder.typicode.com/users';
+const urlPosts = 'https://jsonplaceholder.typicode.com/posts';
+const urlComments = 'https://jsonplaceholder.typicode.com/comments';
+
+module.exports = function fetchData(isPrint = true) {
+  return fetch(urlUsers)
+    .then(res => res.json())
+    .then(users => {
+      let requiredUser = users[0].id;
+      if (isPrint) console.log(`Querying user:\n\t${users[0].name}`);
+      return fetch(`${urlPosts}?userId=${requiredUser}`)
+    })
+    .then(res => res.json())
+    .then(posts => {
+      let requiredPost = posts[0].id;
+      if (isPrint) console.log(`\nQuerying post:\n\t${posts[0].title}`);
+      return fetch(`${urlComments}?postId=${requiredPost}`)
+
+    })
+    .then(res => res.json())
+    .then(comments => {
+      if (isPrint) console.log(`\nFinally found comments!!!`);
+      comments.forEach((comment, i) => {
+        if (isPrint) console.log(`\n${i}: ${comment.body}`);
+      });
+      // throw new Error('Error: no comments');
+      return comments;
+      // return Promise.resolve(comments);
+    })
+    .catch(err => console.log(err.message));
+};