new code added

JavaScript_Advance/arrow_function.js

@@ -6,7 +6,7 @@ let info = {
   firstName: "Swapnil",
   lastName: "Shinde",
   getFullName: () => {
-    return(`My name is ${this.firstName} ${this.lastName}`); // Arrow functions don't have "this" property
+    return (`My name is ${this.firstName} ${this.lastName}`); // Arrow functions don't have "this" property
   }
 }
 
@@ -17,7 +17,7 @@ let newInfo = {
   firstName: "Swapnil",
   lastName: "Shinde",
   getFullName: () => {
-    return(`My name is ${newInfo.firstName} ${newInfo.lastName}`); // If we are using arrow function then directly use the variables as shown
+    return (`My name is ${newInfo.firstName} ${newInfo.lastName}`); // If we are using arrow function then directly use the variables as shown
   }
 }
 
@@ -39,24 +39,34 @@ console.log((new Student).getName()) // Gives error for node versions before 12.
 
 class StudentInfo {
 
-  constructor (firstName,lastName, age, branch, college){ 
-    this.firstName = firstName; 
+  constructor(firstName, lastName, age, branch, college) {
+    this.firstName = firstName;
     this.lastName = lastName;
-    this.age = age; 
+    this.age = age;
     this.branch = branch;
     this.college = college;
   };
 
   getFullName = () => { // Returns full name using string interpolation
-    return(`My name is ${this.firstName} ${this.lastName}`); // If we are using arrow function then directly use the variables as shown
+    return (`My name is ${this.firstName} ${this.lastName}`); // If we are using arrow function then directly use the variables as shown
   };
 
   getBranch = () => { // Returns Branch 
-    return(this.branch);
+    return (this.branch);
   };
 
 }
 
-let Swapnil = new StudentInfo("Swapnil", "Shinde",19, "Computer", "Sies"); // This way we can create new objects with arguments
+let Swapnil = new StudentInfo("Swapnil", "Shinde", 19, "Computer", "Sies"); // This way we can create new objects with arguments
 
-console.log(Swapnil.getFullName()); // Output My name is Swapnil Shinde
+console.log(Swapnil.getFullName()); // Output My name is Swapnil Shinde
+
+//settimeout without arrow function
+setTimeout(function () {
+  console.log("hello world");
+}, 1000);
+
+//settimeout with arrow function
+setTimeout(() => {
+  console.log("hello world");
+}, 0);

JavaScript_Advance/event_loop.js

@@ -4,4 +4,14 @@ setTimeout(() => {
 
 console.log("Last statement"); // This statement gets printed first
 
-// This enables the non blocking using event based management
+// This enables the non blocking using event based management
+
+console.log("a");
+setTimeout(() => {
+  console.log("b")
+}, 2000);
+console.log("c");
+setTimeout(() => {
+  console.log("d");
+}, 0)
+//except answer : a , c , d , b

JavaScript_Advance/filtering_array.js

@@ -2,4 +2,19 @@ const animals = ["cats", "dogs", "bunnies", "birds"];
 
 const start_with_b = animals.filter(name => name.indexOf("b") === 0);
 
-console.log(start_with_b); // ['bunnies', 'birds']
+console.log(start_with_b); // ['bunnies', 'birds']
+
+//function of filter (basic callback for filter)
+const arr = [1, 3, 42, 2, 4, 5];
+function filter(array, callback) {
+    let callback_list = [];
+    for (let i of array) {
+        callback_list.push(callback(i));
+    }
+    return callback_list;
+}
+//modifyable callback function 
+function callback(num) {
+    return Math.pow(num, 2);
+}
+console.log(filter(arr, callback));

JavaScript_Advance/hoisting.js

@@ -23,4 +23,11 @@ elem.innerHTML = x; // Display x in the element
 /* Conclusion :Example 1 gives the same result as Example 2
 so, Hoisting is JavaScript's default behavior of moving all declarations to the top of the current scope
 (to the top of the current script or the current function)
-*/
+*/
+
+console.log(foo);
+let foo = 'foo'; //unable to print due to the hoisting behaviour
+
+console.log(ok);
+var ok = 'this is printing'//var is hoisted
+

JavaScript_Advance/promises.js

@@ -40,7 +40,7 @@ getAsyncDataWithPromises()
   .then(data => {
     // ... use data
   }).catch(e => {
-  // ... handle exception
+    // ... handle exception
   });
 
 // promises promise the nodejs main thread that i'm going to come after doing a particular task
@@ -77,4 +77,25 @@ asyncCall
   // appended with ' bar' to become 'foo bar'
   .then(val => `${val} bar`)
   // console logs 'foo bar'
-  .then(console.log);
+  .then(console.log);
+
+//promise.all();\
+const fs = require('fs');
+const dir = __dirname + '/text/';
+var promisesarray = ["Text file content start after this : "];
+function readfile() {
+  fs.readdir(dir, 'utf-8', (err, File) => {
+    File.forEach(file => {
+      promisesarray.push(new Promise((resolve, reject) => {
+        fs.readFile(dir + file, 'utf-8', (err, data) => {
+          if (err) reject(err);
+          else resolve(data);
+        });
+      }));
+    });
+    Promise.all(promisesarray).then(data => {
+      console.log(data);
+    })
+  });
+}
+readfile();

JavaScript_Advance/while_loop.js

@@ -15,4 +15,9 @@ var n = 1;
 while (n < 6) {
   console.log("n is less than 6. n = " + n);
   n++;
-}
+}
+
+var sum = 1;
+do {
+  console.log(`sum now is ${sum++}`);
+} while (sum <= 100);