completed javascript assignment 8

Q1.js

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+/*
+1. Write a function that can stop execution of a function for the number of 
+milliseconds sent as an argument
+Example:
+  const func = async () => {
+  console.log(“Printing before”)
+  //Call your function here eg. sleep(3000)
+  console.log(“Printing after”)
+}
+*/
+
+const func = async (time) => {
+  console.log("Printing before");
+  setTimeout(() => {
+    console.log(`Executed after ${time} seconds`);
+  }, time);
+  console.log("Printing after");
+};
+
+func(5000);

Q2.js

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+/*
+2.  Using promises - write a function that fetches data from an API endpoint 
+(GET https://reqres.in/api/users ). 
+Log the data into the console once it is received
+*/
+
+//with await
+async function getUsers(url) {
+  let response = await fetch(url);
+  return response.json();
+}
+
+let users = getUsers("https://reqres.in/api/users ");
+users.then((result) => {
+  console.log(result);
+});
+
+//without await
+function getUsersWithoutAwait(url) {
+  fetch(url)
+    .then((res) => res.json())
+    .then((res) => console.log(res))
+    .catch((err) => err);
+}
+
+//this gives required data
+getUsersWithoutAwait("https://reqres.in/api/users ");
+
+//this gives Promise { <pending> }
+//Bcoz of JS Engine-> log function gets executed first, before even the promise resolves
+// console.log({ users });

Q3.js

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+/*
+3. What will be printed to the console when the promise resolves and when it rejects?
+const testAsyncFunction = () =>{
+return new Promise((resolve, reject) =>{
+if (Math.random() > 0.5) {
+resolve('Test Resolve');
+} else {
+reject('Test Reject');
+}
+}).catch((err) =>{
+console.log('Error caught in testAsyncFunction: ', err);
+});
+};
+testAsyncFunction()
+.then((res) =>{
+console.log('Response in then block: ', res);
+})
+.catch((err) => console.log('Error in catch block: ', err));
+*/
+
+const testAsyncFunction = () => {
+  return new Promise((resolve, reject) => {
+    if (Math.random() > 0.5) {
+      resolve("Test Resolve");
+    } else {
+      reject("Test Reject");
+    }
+  }).catch((err) => {
+    console.log("Error caught in testAsyncFunction: ", err);
+  });
+};
+
+testAsyncFunction()
+  .then((res) => {
+    console.log("Response in then block: ", res);
+  })
+  .catch((err) => console.log("Error in catch block: ", err));
+
+//When the promise resolves, we get - "Response in then block:  Test Resolve"
+//As parameter passed in resolve function gets passed in then function of promise.
+
+//When the promise rejects, we get -
+//Error caught in testAsyncFunction:  Test Reject
+// Response in then block:  undefined
+
+//As we have written catch in the function itself the error gets executed there
+//and in the next catch it returns undefined. So we get result as above

Q4.js

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+/*
+4.  What will be printed to the console?
+const testAsyncFunction = () =>{
+return Promise.reject('Test static reject');
+};
+testAsyncFunction()
+.then((res) =>{
+console.log('Response in then block', res);
+})
+.catch((err) => console.log('Error in catch block', err));
+*/
+
+const testAsyncFunction = () => {
+  return Promise.reject("Test static reject");
+};
+testAsyncFunction()
+  .then((res) => {
+    console.log("Response in then block", res);
+  })
+  .catch((err) => console.log("Error in catch block", err));
+
+//Output-Error in catch block Test static reject
+
+//The static Promise.reject function returns a Promise that is rejected.
+//It is a generic method

Q5.js

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+/*
+5. What will be printed to the console?
+const testAsyncFunction = () =>{
+return new Promise((resolve, reject) =>{
+if (Math.random() > 0.5) {
+resolve('Test Resolve');
+} else {
+reject('Test Reject');
+}
+}).catch((err) =>{
+console.log('Error caught in testAsyncFunction', err);
+throw new Error('Forced error');
+});
+};
+testAsyncFunction()
+.then((res) =>{
+console.log('Response in then block: ', res);
+})
+.catch((err) => console.log('Error in catch block: ', err));
+
+*/
+
+const testAsyncFunction = () => {
+  return new Promise((resolve, reject) => {
+    if (Math.random() > 0.5) {
+      resolve("Test Resolve");
+    } else {
+      reject("Test Reject");
+    }
+  }).catch((err) => {
+    console.log("Error caught in testAsyncFunction", err);
+    throw new Error("Forced error");
+  });
+};
+testAsyncFunction()
+  .then((res) => {
+    console.log("Response in then block: ", res);
+  })
+  .catch((err) => {
+    console.log("Error in catch block: ", err);
+  });
+
+//When promise resolves-
+//Output:-Response in then block:  Test Resolve
+
+//When promise rejects-
+/*Output:-Error caught in testAsyncFunction Test Reject
+          Error in catch block:  Error: Forced error
+            at /home/josh/javascript_training/Q5.js:32:11
+*/
+
+/*
+we have thrown a new error in the function of catch block of previous promise,
+which gets catched in the next execution
+ */

Q6.js

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+/*
+Q6. Create a promise that makes a fetch call, 
+  but resolves with the data only 2 seconds after the data
+  has been received in the fetch.
+
+*/
+
+const getUsers = (url) => fetch(url);
+
+const newFunc = () => {
+  return new Promise((res, rej) => {
+    getUsers("https://reqres.in/api/users")
+      .then((users) => {
+        if (!users) {
+          rej("Not Found...");
+        }
+        console.log("receivedData");
+        setTimeout(() => {
+          res(users.json());
+        }, 2000);
+      })
+      .catch((err) => {
+        console.log(err);
+      });
+  });
+};
+
+newFunc()
+  .then((data) => {
+    console.log(data);
+  })
+  .catch((err) => {
+    console.log(err);
+  });

Q7.js

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+/*
+Q7. Create a promise that makes a fetch call, 
+  but resolves with the data only 2 seconds after the data
+  has been received in the fetch.
+(with async and await)
+*/
+
+//With Async and Await
+
+const getUsers = async (url) => await fetch(url);
+
+const func = (url) => {
+  return new Promise((res, rej) => {
+    getUsers(url)
+      .then((users) => {
+        if (!users) {
+          rej("Not Found...");
+        }
+        console.log("receivedData");
+        setTimeout(() => {
+          res(users.json());
+        }, 2000);
+      })
+      .catch((err) => {
+        console.log("Custom Error ", err);
+      });
+  });
+};
+
+func("https://reqres.in/api/users").then((users) => console.log(users));