NW7 | Sue Mohamadi | Module-Structuring-and-Testing-Data | module 2/ week 3 (Sprint-3 exercises)

Sprint-1/errors/0.js

@@ -1,2 +1,3 @@
-This is just an instruction for the first activity - but it is just for human consumption
-We don't want the computer to run these 2 lines - how can we solve this problem?
+/*This is just an instruction for the first activity - but it is just for human consumption
+We don't want the computer to run these 2 lines - how can we solve this problem? 
+because these sentences were not nested inside JS's comment syntax.*/

Sprint-1/errors/1.js

@@ -1,4 +1,6 @@
 // trying to create an age variable and then reassign the value by 1
-
-const age = 33;
+/*when const is used to create a variable, it can not be reassigned. So for this practice, i replace
+with let to fix this error.*/ 
+let age = 33;
 age = age + 1;
+console.log(age);

Sprint-1/errors/2.js

@@ -1,5 +1,9 @@
 // Currently trying to print the string "I was born in Bolton" but it isn't working...
 // what's the error ?
+/*the answer is related to the order that the code was written. the variable declaration followed console.log
+instead of preceding it resulting in a reference error. I cut the variable declaration and pasted it above
+console.log to resolve the problem.*/ 
 
-console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+

Sprint-1/errors/3.js

@@ -1,9 +1,12 @@
-const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
+const cardNumber = 4533787178994213; // const cardNumber = `${4533787178994213}` also fixes the error by changing data type to string.
+const last4Digits = cardNumber.toString().slice(-4);
+console.log(`The last 4 digits of the card number are: ${last4Digits}`);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
 // However, the code isn't working
 // Before running the code, make and explain a prediction about why the code won't work
 // Then run the code and see what error it gives.
 // Consider: Why does it give this error? Is this what I predicted? If not, what's different?
+/* the answer: slice() method does only work on strings and arrays. it does not work on numbers.
+so I fixed it by changing the expression in Last4Digits variable.  */
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value

Sprint-1/errors/4.js

@@ -1,2 +1,5 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+let HourClockTime = "20:53";
+hourClockTime = "08:53"; 
+console.log(hourClockTime); // Output: 08:53
+/*Javascript variables can not be started with numbers. I changed const to let so that the variable can 
+be reassigned to a new value. */

Sprint-1/exercises/count.js

@@ -1,6 +1,8 @@
 let count = 0;
 
 count = count + 1;
+/*line 3 reassigns the value that was passed onto count variable by using an arithmetic operator to add 
+1 to count variable's value.*/
 
 // Line 1 is a variable declaration, creating the count variable with an initial value of 0
 // Describe what line 3 is doing, in particular focus on what = is doing

Sprint-1/exercises/decimal.js

@@ -1,9 +1,15 @@
 const num = 56.5678;
-
+console.log(num);
 // You should look up Math functions for this exercise https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Math
 
 // Create a variable called wholeNumberPart and assign to it an expression that evaluates to 56 ( the whole number part of num )
 // Create a variable called decimalPart and assign to it an expression that evaluates to 0.5678 ( the decimal part of num )
 // Create a variable called roundedNum and assign to it an expression that evaluates to 57 ( num rounded to the nearest whole number )
 
 // Log your variables to the console to check your answers
+const wholeNumberPart = Math.floor(num);
+console.log("wHole number is:"+ wholeNumberPart);
+const decimalPart = num - wholeNumberPart;
+console.log("decimal part is:"+ decimalPart);
+const roundedNum = Math.round(num);
+console.log("rounded number is:"+ roundedNum);

Sprint-1/exercises/initials.js

@@ -2,5 +2,9 @@ let firstName = "Creola";
 let middleName = "Katherine";
 let lastName = "Johnson";
 
+
 // Declare a variable called initials that stores the first character of each string.
 // This should produce the string "CKJ", but you must not write the characters C, K, or J in the code of your solution.
+let initials = firstName.charAt(0) + middleName.charAt(0) + lastName.charAt(0);
+
+console.log("initials are:" + initials);

Sprint-1/exercises/paths.js

@@ -10,9 +10,21 @@
 // (All spaces in the "" line should be ignored. They are purely for formatting.)
 
 const filePath = "/Users/mitch/cyf/Module-JS1/week-1/interpret/file.txt";
+console.log(filePath);
 const lastSlashIndex = filePath.lastIndexOf("/");
-const base = filePath.slice(lastSlashIndex + 1);
+console.log(lastSlashIndex);
+const base = filePath.slice(lastSlashIndex+1);
+console.log(base);
 console.log(`The base part of ${filePath} is ${base}`);
 
 // Create a variable to store the dir part of the filePath variable
-// Create a variable to store the ext part of the variable
+const dir = filePath.slice(0,lastSlashIndex+1);
+console.log(dir);
+// Create a variable to store the ext part of the variables.
+const lastDotIndex = filePath.lastIndexOf(".");
+const ext = filePath.slice(lastDotIndex+1);
+console.log(ext);
+
+//another way to extract ext part of filePath string is: 
+const ext2 = filePath.split(".").pop();
+console.log(ext2);

Sprint-1/exercises/random.js

@@ -2,8 +2,12 @@ const minimum = 1;
 const maximum = 100;
 
 const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
+/*due to rules of precedence, parenthesis executes first. Inside parenthesis, subtraction executes first, 
+then addition executes.*/
+console.log("random number:" + num);
+/*num keeps changing because Math.random() function outputs a different random value between 0 and 1 every time it runs. */
 
-// In this exercise, you will need to work out what num represents?
+// In this exercise, you will need to work out what num represents? answer: a numerical value 
 // Try breaking down the expression and using documentation to explain what it means
 // It will help to think about the order in which expressions are evaluated
 // Try logging the value of num and running the program several times to build an idea of what the program is doing

Sprint-1/explore/chrome.md

@@ -10,9 +10,9 @@ Let's try an example.
 In the Chrome console,
 invoke the function `alert` with an input string of `"Hello world!"`;
 
-What effect does calling the `alert` function have?
+What effect does calling the `alert` function have? I get a pop-up window which prints my message.
 
 Now try invoking the function `prompt` with a string input of `"What is your name?"` - store the return value of your call to `prompt` in an variable called `myName`.
 
-What effect does calling the `prompt` function have?
-What is the return value of `prompt`?
+What effect does calling the `prompt` function have? I get a pop-up notification asking the question and providing a box to get the input.
+What is the return value of `prompt`? it outputs the input of that question.

Sprint-1/explore/objects.md

@@ -4,13 +4,21 @@ In this activity, we'll explore some additional concepts that you'll encounter i
 
 Open the Chrome devtools Console, type in `console.log` and then hit enter
 
-What output do you get?
+What output do you get? 
+ƒ log() { [native code] } 
+(log is a function (that's what the ƒ symbol means).
+It's a "native" function, meaning it's built into the browser's JavaScript engine)
 
-Now enter just `console` in the Console, what output do you get back?
+Now enter just `console` in the Console, what output do you get back? 
+console {debug: ƒ, error: ƒ, info: ƒ, log: ƒ, warn: ƒ, …}
+console is an object.
+It contains multiple functions (methods) like debug, error, info, log, warn, etc.
 
 Try also entering `typeof console`
+it returns object because console is an object.
 
 Answer the following questions:
 
-What does `console` store?
-What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean?
+What does `console` store? methods. console is a toolbox full of different tools.
+What does the syntax `console.log` or `console.assert` mean? In particular, what does the `.` mean? 
+The dot tells JavaScript "look inside this object (console) and give me access to this specific method (log or assert)"

Sprint-1/interpret/percentage-change.js

@@ -2,7 +2,7 @@ let carPrice = "10,000";
 let priceAfterOneYear = "8,543";
 
 carPrice = Number(carPrice.replaceAll(",", ""));
-priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
 
 const priceDifference = carPrice - priceAfterOneYear;
 const percentageChange = (priceDifference / carPrice) * 100;
@@ -12,11 +12,17 @@ console.log(`The percentage change is ${percentageChange}`);
 // Read the code and then answer the questions below
 
 // a) How many function calls are there in this file? Write down all the lines where a function call is made
+/*Line 4: Number() replaceAll() | line 5: Number() replaceAll() | line 10: console.log() */
 
 // b) Run the code and identify the line where the error is coming from - why is this error occurring? How can you fix this problem?
+/*Line 4; lack of comma between "," and ""; add a comma between them. */
 
 // c) Identify all the lines that are variable reassignment statements
+/*Line 4, line 5 */
 
 // d) Identify all the lines that are variable declarations
+/*Line 1, line 2, line 7, line 8 */
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+/*firstly, replaceAll string function gets executed. it replaces , in the carPrice variable's value with "". secondly, Number function changes 
+carPrice's data type from string to numeric. */

Sprint-1/interpret/time-format.js

@@ -11,14 +11,31 @@ console.log(result);
 
 // For the piece of code above, read the code and then answer the following questions
 
-// a) How many variable declarations are there in this program?
+// a) How many variable declarations are there in this program? 6
 
-// b) How many function calls are there?
+// b) How many function calls are there? 1
 
 // c) Using documentation, explain what the expression movieLength % 60 represents
+/*it means dividing 8784 by 60 and output the remainder value of this division. */
+
 
 // d) Interpret line 4, what does the expression assigned to totalMinutes mean?
+/*It calculates the movie length in minutes */
 
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
+/*it shows how long the movie is in hour/minute/seconds format like 2:34:44 . A better name is: totalMovieLength */
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+/*an easier code would be:
+const movieLength = 8784;
+const totalMovieLength = `${Math.floor(movieLength / 3600)}:${Math.floor((movieLength % 3600) / 60)}:${(movieLength%3600) % 60}`;
+
+Or 
+const movieLength = 8784;
+const hour = Math.floor(movieLength/3600);
+const minute = Math.floor((movieLength%3600)/60);
+const second = (movieLength%3600)%60;
+console.log(`movie length is ${hour}:${minute}:${second}`);
+*/
+

Sprint-1/interpret/to-pounds.js

@@ -1,19 +1,21 @@
-const penceString = "399p";
-
-const penceStringWithoutTrailingP = penceString.substring(
+// variable declaration; assignment of value 399p to penceString variable
+const penceString = "399p"; 
+// variable declaration; the expression takes the p out of penceString and outputs 399
+const penceStringWithoutTrailingP = penceString.substring( 
   0,
   penceString.length - 1
 );
-
+//variable declaration; the expression adds 0 to the start of the penceStringWithoutTrailingP if it has less than 3 characters
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
+//variable declaration; the expression takes out 99 from paddedPenceNumberString and outputs 3
 const pounds = paddedPenceNumberString.substring(
   0,
   paddedPenceNumberString.length - 2
 );
-
+//variable declaration; the expression takes out 3 from paddedPenceNumberString, then adds 0 to the end of if its characters are less than 2
 const pence = paddedPenceNumberString
   .substring(paddedPenceNumberString.length - 2)
-  .padEnd(2, "0");
+  .padEnd(2, "0"); //output:99
 
 console.log(`£${pounds}.${pence}`);
 

Sprint-2/debug/0.js

@@ -1,7 +1,8 @@
 // Predict and explain first...
 
 function multiply(a, b) {
-  console.log(a * b);
+  let multiplyOutput = Math.abs(a*b);
+  return multiplyOutput;
 }
 
-console.log(`The result of multiplying 10 and 32 is ${multiply(10, 32)}`);
+console.log(`The result of multiplying 10 and 32 is ${multiply(10, -5)}`);

Sprint-2/debug/1.js

@@ -1,8 +1,7 @@
 // Predict and explain first...
 
 function sum(a, b) {
-  return;
-  a + b;
+  return a+b;
 }
 
 console.log(`The sum of 10 and 32 is ${sum(10, 32)}`);

Sprint-2/debug/2.js

@@ -1,9 +1,10 @@
 // Predict and explain first...
 
-const num = 103;
+// const num = 103; this variable is a universal one. function needs its local variable.
 
-function getLastDigit() {
-  return num.toString().slice(-1);
+function getLastDigit(num) {
+  let lastDigit = num.toString().slice(-1);
+  return lastDigit;
 }
 
 console.log(`The last digit of 42 is ${getLastDigit(42)}`);

Sprint-2/errors/0.js

@@ -3,7 +3,10 @@
 // call the function capitalise with a string input
 // interpret the error message and figure out why an error is occurring
 
-function capitalise(str) {
-  let str = `${str[0].toUpperCase()}${str.slice(1)}`;
-  return str;
+function capitalise(x) {
+  let z = `${x[0].toUpperCase()}${x.slice(1)}`; //inja age + bezaram toye output mishe + lol
+  return z;
 }
+ /*khob error chi bood? i gave variable x to be my parameter. so now inside the function, if  i want to create a new
+ variable, it needs a new name! */
+console.log(capitalise("moein"));

Sprint-2/errors/1.js

@@ -3,11 +3,21 @@
 // Why will an error occur when this program runs?
 // Try playing computer with the example to work out what is going on
 
-function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
+/* function convertToPercentage(decimalNumber) {
+   decimalNumber = 0.5; //remove this!
   const percentage = `${decimalNumber * 100}%`;
 
   return percentage;
 }
 
-console.log(decimalNumber);
+console.log(decimalNumber); //it must become console.log(convertToPercentage(0.25)); */
+//correct version is written down:
+
+function convertToPercentage(decimalNumber) {
+
+ const percentage = `${decimalNumber * 100}%`;
+
+ return percentage;
+}
+
+console.log(convertToPercentage(0.8));

Sprint-2/errors/2.js

@@ -3,8 +3,12 @@
 
 // this function should square any number but instead we're going to get an error
 
-function square(3) {
+/*function square(3) { //put a variable here for parameter! in this case, name in 'num'
+    return num * num;
+} */
+//correct version is written below:
+function square(num) { 
     return num * num;
 }
-
+console.log(square(87));
 

Sprint-2/extend/format-time.js

@@ -1,13 +1,39 @@
 // This is the latest solution to the problem from the prep.
 // Your task is to write tests for as many different groups of input data or edge cases as you can, and fix any bugs you find.
 
+/* this function does not cover edge cases and minutes.
 function formatAs12HourClock(time) {
   const hours = Number(time.slice(0, 2));
   if (hours > 12) {
     return `${hours - 12}:00 pm`;
   }
   return `${time} am`;
 }
+  */
+//this function below is an updated, advanced version of the function above.
+function formatAs12HourClock(time) {
+  let converted = Number(time.slice(0,2));
+  let minutes = time.slice(-3);
+  //consider special cases first.
+  if (converted === 0 ) {
+    return "00:00 midnight";
+  }
+  else if (converted === 24) {
+    let specialCase24 = 24-12;
+    return `${specialCase24}${minutes} am`
+
+  }
+  else if (converted === 12) {
+    return `${converted}${minutes} pm`;
+  }
+  else if (converted>12){
+    let above12 = converted-12;
+    return `${above12}${minutes} pm`;
+  }
+  else{
+    let below12 = converted.toString().padStart(2,"0");
+    return `${below12}${minutes} am`;}
+}
 
 const currentOutput = formatAs12HourClock("08:00");
 const targetOutput = "08:00 am";