CodeYourFuture · howard-ss · Dec 12, 2022 · Dec 12, 2022 · Dec 13, 2022 · Dec 13, 2022
diff --git a/1-exercises/A-undefined/exercise.js b/1-exercises/A-undefined/exercise.js
@@ -10,27 +10,41 @@
 */
 
 // Example 1
+//We are declaring a variable here, but never assigning it to a value - 
+//therefore the variable is undefined.
 let a;
-console.log(a);
+console.log(a);  // There's no value assigned to variable  a
 
 
 // Example 2
+//Explanation: Here, we are assigning the value returned from the function 
+//             sayHello to the variable hello.
+// But sayHello doesn't actually return anything, so hello is undefined.
 function sayHello() {
-    let message = "Hello";
+    let message = "Hello"; // There's no output from this function.
 }
 
 let hello = sayHello();
-console.log(hello);
+console.log(hello);   //log 'hello', but due to sayHello()function  is undefined, so it's logged undefined as well.
 
 
 // Example 3
+// Explanation: Here, we have a function which takes a parameter called user.
+//          But when we call the function, we're not passing in any arguments - there's nothing in the brackets!
+//          Because of this, the value of the user parameter inside the function is undefined.
+
 function sayHelloToUser(user) {
     console.log(`Hello ${user}`);
 }
 
-sayHelloToUser();
+sayHelloToUser();  // There's no argument assigned when call sayHelloToUser()function.
 
 
 // Example 4
+// Explanation: Here, we are trying to retrieve an element from the array at index 3.
+//       But in this case, the array doesn't have any value at index 3 - 
+//       it only has values at indexes 0, 1 and 2.
+//       Therefore, retrieving an element from index 3 will give us undefined.
+
 let arr = [1,2,3];
-console.log(arr[3]);
+console.log(arr[3]);  // There's no 4th element in array, so it logs 'undefined'.
diff --git a/1-exercises/B-while-loop/exercise.js b/1-exercises/B-while-loop/exercise.js
@@ -1,12 +1,25 @@
 /*
-    while loops can be useful when you want to execute some code as long as some condition is true.    
+    while loops can be useful when you want to execute some code as long as
+    some condition is true.    
 
-    Using a while loop, complete the function below so it logs (using console.log) the first n even numbers as a comma-seperated string.
-    The list of numbers should start with 0. n is being passed in as a parameter.
+    Using a while loop, complete the function below so it logs (using 
+    console.log) the first n even numbers as a comma-separated string.
+    The list of numbers should start with 0.
+    n is being passed in as a parameter.
 */
 
 function evenNumbers(n) {
-    // TODO
+  // TODO
+  // initializing an array to hold even numbers:
+  let result = [];
+  let i = 0;
+  while (i < n) {
+    result.push(i * 2);
+    i++;
+  }
+  // joining the elements of the array together as a string
+  // Read more here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/join
+    console.log(result.join())
 }
 
 evenNumbers(3); // should output 0,2,4

diff --git a/1-exercises/C-while-loop-with-array/exercise.js b/1-exercises/C-while-loop-with-array/exercise.js
@@ -1,7 +1,9 @@
 /*
     Loops can be useful when working with arrays.
-    In the below example, imagine we've defined an array holding the birthdays of your closest friends.
-    Use a while loop to search through the array until you find the first birthday in July, then return that birthday from the function.
+    In the below example, imagine we've defined an array holding the birthdays
+    of your closest friends.
+    Use a while loop to search through the array until you find the first
+    birthday in July, then return that birthday from the function.
 */
 
 const BIRTHDAYS = [
@@ -18,6 +20,21 @@ const BIRTHDAYS = [
 
 function findFirstJulyBDay(birthdays) {
     // TODO
+     let i=0;
+     while(i<birthdays.length){
+
+    // using includes()methods
+    // let newBday = birthdays.find(x => x.includes('July'));
+    //     return newBday;
+    //     i++;
+    // 
+
+    //or using startsWith()method:
+    if(BIRTHDAYS[i].startsWith('July')){
+        return BIRTHDAYS[i];
+    }
+    i++
+    }
 }
 
 console.log(findFirstJulyBDay(BIRTHDAYS)); // should output "July 11th"
diff --git a/1-exercises/D-do-while/exercise.js b/1-exercises/D-do-while/exercise.js
@@ -1,15 +1,55 @@
 /*
-    Sometimes when using loops, we'll want to execute the body of the loop at least once. We can make sure this happens by using a do-while loop.
-        - If the condition in a while loop is initially false, the body of the loop will never execute
-        - But in a do-while loop, because the condition is checked after the body, we know that it will always execute at least once
+    Sometimes when using loops, we'll want to execute the body of the loop 
+    at least once. We can make sure this happens by using a do-while loop.
+        - If the condition in a while loop is initially false, the body of 
+          the loop will never execute
+        - But in a do-while loop, because the condition is checked after
+          the body, we know that it will always execute at least once
 
-    Using a do-while loop, write a function which returns the sum of the first n even numbers (starting from 0)
+    Using a do-while loop, write a function which returns the sum of the 
+    first n even numbers (starting from 0)
 */
 
 function evenNumbersSum(n) {
-    // TODO
-}
+  // TODO
+
+  //1.own solution: initialize first even number is 0, sum is 0, counter from 0;
+  // let currEvenNumber = 0;
+  // let sum = 0;
+  // let i = 0;
+  // do {
+  // //sum of first n even number(0):
+  //   sum += currEvenNumber;
+  // //next even number:
+  //   currEvenNumber += 2;
+  // //next counter:
+  //   i++;
+  // } while (i < n);    //condition
+  // return sum;         //return final output when condition is false.
+
+//2.solution from google classroom  review:
+   let sum = 0;
+   let i=0;    
+   do {
+    sum += (i * 2);
+    i++;
+   }while(i < n);
+   return sum;
 
+}
+//   for loop:  solution 
+//      let currEvenNumber = 0,
+//        sum = 0;
+//      // sum of first n even numbers
+//      for (let i = 0; i < n; i++) {
+//        sum += currEvenNumber;
+//        // next even number
+//        currEvenNumber += 2;
+//      }
+//      // required sum
+//      return sum;
+//    }
+
 console.log(evenNumbersSum(3)); // should output 6
 console.log(evenNumbersSum(0)); // should output 0
-console.log(evenNumbersSum(10)); // should output 90
+console.log(evenNumbersSum(10)); //should output 90
diff --git a/1-exercises/E-for-loop/exercise1.js b/1-exercises/E-for-loop/exercise1.js
@@ -6,9 +6,14 @@
 
 
 // Change the below code to use a for loop instead of a while loop.
-let i = 0;
-while(i < 26) {
-    console.log(String.fromCharCode(97 + i));
-    i++;
+//let i = 0;
+//while(i < 26) {
+//    console.log(String.fromCharCode(97 + i));
+//    i++;
+//}
+
+for (let i=0; i< 26; i++){
+    console.log((String.fromCharCode(97 + i)).toUpperCase());
 }
+
 // The output shouldn't change.
diff --git a/1-exercises/E-for-loop/exercise2.js b/1-exercises/E-for-loop/exercise2.js
@@ -1,13 +1,16 @@
 /*
-    for loops can be useful when we already know exactly how many times we want to loop.
+    for loops can be useful when we already know exactly how many times 
+    we want to loop.
 
     Below we have 2 arrays which have exactly the same number of values.
         - The first array is a list of writers
         - The second array is a list of ages
-    The writers in the first array correspond with the ages in the second array.
+    The writers in the first array correspond with the ages in the second 
+    array.
     For example, Virginia Woolf is 59 years old.
 
-    Using a for loop, output to the console a line about the age of each writer.
+    Using a for loop, output to the console a line about the age of each 
+    writer.
 */
 
 const WRITERS = [
@@ -27,7 +30,23 @@ const AGES = [
 ];
 
 // TODO - Write for loop code here
+  //1.own solution:
+//for (let i=0, j=0; i< WRITERS.length, j< AGES.length;i++, j++){
+//    console.log(`${WRITERS[i]} is ${AGES[j]} years old`);
+//}
 
+   //2. solution from google classroom review:
+      for (let i=0; i<WRITERS.length;i++){
+        // Because we want to retrieve the element at the same index for 
+        // both arrays, we can re-use the same variable i
+        console.log(`${WRITERS[i]} is ${AGES[i]} years old`)
+      }
+
+//for (let j=0; j< b.length; j++){
+//    return AGES[j];
+//}
+
+//console.log(writersAges(WRITERS,AGES))
 /*
 The output should look something like this:
 

diff --git a/1-exercises/F-for-of-loop/exercise.js b/1-exercises/F-for-of-loop/exercise.js
@@ -10,7 +10,14 @@ let tubeStations = [
     "Oxford Street",
     "Tottenham Court Road"
 ];
+for ( let tube of tubeStations){
+    console.log(tube)
+}
 
 
-// TODO Use a for-of loop to capitalise and output each letter in the string seperately.
+// TODO Use a for-of loop to capitalise and output each letter in the string 
+//      seperately.
 let str = "codeyourfuture";
+for (let letter of str) {
+    console.log(letter.toUpperCase());
+}
diff --git a/2-mandatory/1-weather-report.js b/2-mandatory/1-weather-report.js
@@ -2,18 +2,36 @@
     Imagine we're making a weather app!
 
     We have a list of cities that the user wants to track.
-    We also already have a temperatureService function which will take a city as a parameter and return a temparature.
+    We also already have a temperatureService function which will take a city 
+    as a parameter and return a temperature.
 
     Implement the function below:
         - take the array of cities as a parameter
-        - return an array of strings, which is a statement about the temperature of each city.
-            For example, "The temperature in London is 10 degrees"
+        - return an array of strings, which is a statement about the 
+          temperature of each city.
+          For example, "The temperature in London is 10 degrees"
         - Hint: you can call the temperatureService function from your function
 */
 
-function getTemperatureReport(cities) {
+ function getTemperatureReport(cities) {
     // TODO
-}
+
+    //for loop:
+    // let arr = [];
+    //    for (let i=0; i < cities.length; i++){
+    //    arr.push(`The temperature in ${cities[i]} is ${temperatureService(cities[i])} degrees`)
+    // }
+    // return arr;
+
+    //for ... of: (from google classroom review)
+     let report = [];
+     for (let city of cities){
+        let temperature = temperatureService(city);
+        report.push(`The temperature in ${city} is ${temperature} degrees`);
+     }
+     return report;
+
+ }
 
 
 /* ======= TESTS - DO NOT MODIFY ===== */

diff --git a/2-mandatory/2-retrying-random-numbers.js b/2-mandatory/2-retrying-random-numbers.js
@@ -1,5 +1,6 @@
 /*
-    In the below example, we want to keep calling generateRandomNumber until we get a value that is > 50.
+    In the below example, we want to keep calling generateRandomNumber until
+    we get a value that is > 50.
     Implement this using a do-while loop.
 */
 
@@ -10,7 +11,12 @@ function generateRandomNumber() {
 }
 
 function getRandomNumberGreaterThan50() {
-    // TODO - implement using a do-while loop
+  // TODO - implement using a do-while loop
+  let x;
+  do {
+    x = generateRandomNumber();
+  } while (x <= 50); //keep trying until we get a number that is > 50
+  return x;
 }
 
 /* ======= TESTS - DO NOT MODIFY ===== */