LONDON_JAN25 | KHALIL ALI | STRUCTURING_AND_TESTING_DATA | SPRINT 1 | WEEK 4

Sprint-1/1-key-exercises/1-count.js

@@ -4,3 +4,8 @@ count = count + 1;
 
 // 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
+/* Line 3 is reassignment for the variable count.
+   we start from the right hand part so  0 + 1 = 1
+   the " = " in line 3 means assigning the right hand part to the left hand var.  
+   count = 1 ;
+*/

Sprint-1/1-key-exercises/2-initials.js

@@ -5,7 +5,8 @@ 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 = ``;
+let initials = firstName[0] + middleName[0] + lastName[0];
+console.log(initials)
 
 // https://www.google.com/search?q=get+first+character+of+string+mdn
 

Sprint-1/1-key-exercises/3-paths.js

@@ -17,7 +17,10 @@ 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 = ;
-const ext = ;
+const dir = filePath.slice(0, lastSlashIndex)
+const ext = filePath.slice(lastSlashIndex + 5)
+
+console.log("dir :", dir)
+console.log("ext :", ext)
 
 // https://www.google.com/search?q=slice+mdn

Sprint-1/1-key-exercises/4-random.js

@@ -7,3 +7,16 @@ const num = Math.floor(Math.random() * (maximum - minimum + 1)) + minimum;
 // 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
+
+console.log("num value is :", num)
+/*
+Math.random():returns a random number between n = [ 0 , 1 [ .
+Math.floor() :returns the previous real number of a decimal number .
+num = Math.floor (n*(100 - 1 + 1) + 1 ;
+num = Math.floor (n*100 + 1)
+num = Math.floor (100n + 1)
+
+num range between : [ 1 , 100 ]  
+num range between : [ minimum , maximum ]
+
+*/

Sprint-1/2-mandatory-errors/0.js

@@ -1,2 +1,9 @@
+/*
 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?
+We don't want the computer to run these 2 lines - how can we solve this problem?
+*/
+
+/*
+ * to add a comment you have two options : 
+  1- // add one line comment
+  2- /*add multiline comment */

Sprint-1/2-mandatory-errors/1.js

@@ -2,3 +2,7 @@
 
 const age = 33;
 age = age + 1;
+
+/*
+to define a variable with reassign feature you should use `let` instead of `const` 
+*/

Sprint-1/2-mandatory-errors/2.js

@@ -1,5 +1,11 @@
 // Currently trying to print the string "I was born in Bolton" but it isn't working...
 // what's the error ?
 
+const cityOfBirth = "Bolton"; 
 console.log(`I was born in ${cityOfBirth}`);
-const cityOfBirth = "Bolton";
+
+
+/*code is rendered line by line.
+ * so you should define the variable cityOfBirth first
+ * then you can use it
+ */

Sprint-1/2-mandatory-errors/3.js

@@ -1,4 +1,4 @@
-const cardNumber = 4533787178994213;
+const cardNumber = "4533787178994213";
 const last4Digits = cardNumber.slice(-4);
 
 // The last4Digits variable should store the last 4 digits of cardNumber
@@ -7,3 +7,8 @@ const last4Digits = cardNumber.slice(-4);
 // 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?
 // Then try updating the expression last4Digits is assigned to, in order to get the correct value
+console.log(last4Digits)
+
+/*slice() is a function takes only string array as an argument.
+ * thats why we changed cardNumber 
+ */

Sprint-1/2-mandatory-errors/4.js

@@ -1,2 +1,6 @@
-const 12HourClockTime = "20:53";
-const 24hourClockTime = "08:53";
+const HourClockTime24 = "20:53";
+const hourClockTime12 = "08:53";
+
+/*variables names can not start with a number.
+ * 
+ */

Sprint-1/3-mandatory-interpret/1-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;
@@ -20,3 +20,9 @@ console.log(`The percentage change is ${percentageChange}`);
 // d) Identify all the lines that are variable declarations
 
 // e) Describe what the expression Number(carPrice.replaceAll(",","")) is doing - what is the purpose of this expression?
+
+// a) 3 times . lines (4,5,10)
+// b) line 5 . syntax error in replaceAll function. add comma
+// c) 4 , 5 lines
+// d) 1 , 2 , 7 , 8 lines
+// e) replace each "," in carPrice with nothing which means : delete each comma 

Sprint-1/3-mandatory-interpret/2-time-format.js

@@ -23,3 +23,10 @@ console.log(result);
 // e) What do you think the variable result represents? Can you think of a better name for this variable?
 
 // f) Try experimenting with different values of movieLength. Will this code work for all values of movieLength? Explain your answer
+
+// a) 6 times
+// b) 1 time
+// c) the reminder after applying division (movieLength / 60) which equals to 24
+// d) number of minutes in movieLength
+// e) movieDuration
+// f) yes it will work for all real positive values of movieLength

Sprint-1/3-mandatory-interpret/3-to-pounds.js

@@ -1,19 +1,11 @@
 const penceString = "399p";
 
-const penceStringWithoutTrailingP = penceString.substring(
-  0,
-  penceString.length - 1
-);
+const penceStringWithoutTrailingP = penceString.substring(0, penceString.length - 1);
 
 const paddedPenceNumberString = penceStringWithoutTrailingP.padStart(3, "0");
-const pounds = paddedPenceNumberString.substring(
-  0,
-  paddedPenceNumberString.length - 2
-);
+const pounds = paddedPenceNumberString.substring(0,paddedPenceNumberString.length - 2);
 
-const pence = paddedPenceNumberString
-  .substring(paddedPenceNumberString.length - 2)
-  .padEnd(2, "0");
+const pence = paddedPenceNumberString.substring(paddedPenceNumberString.length - 2).padEnd(2, "0");
 
 console.log(`£${pounds}.${pence}`);
 
@@ -25,3 +17,8 @@ console.log(`£${pounds}.${pence}`);
 
 // To begin, we can start with
 // 1. const penceString = "399p": initialises a string variable with the value "399p"
+// 3. substring() : cuts a part of the whole string. in this line we remove "p" from penceString.
+// 5. padStart() : add character to a string. in this line we check the string length is three,if not we add "0" to the start
+// 6. accounts the number of pounds which is 3
+// 8. accounts the number of pounds which is 99. in this line we check the string length is two,if not we add "0" to the start
+// 10. 3.99