Complete Sprint 2 error exercises

Author: maryam-devio

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

@@ -1,4 +1,7 @@
-// trying to create an age variable and then reassign the value by 1
+// The error occurs because age is declared with const, so its value cannot be reassigned.
+// The next line tries to assign a new value to age, which causes a TypeError.
+// Using let fixes the error because let allows the variable to be reassigned.
 
-const age = 33;
+let age = 33;
 age = age + 1;
+console.log(age);

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

@@ -1,5 +1,10 @@
 // Currently trying to print the string "I was born in Bolton" but it isn't working...
 // what's the error ?
 
-console.log(`I was born in ${cityOfBirth}`);
 const cityOfBirth = "Bolton";
+console.log(`I was born in ${cityOfBirth}`);
+
+// The error occurs because cityOfBirth is accessed before it has been initialized.
+// Variables declared with const cannot be accessed before their declaration is executed.
+// This causes a ReferenceError because the variable is in the Temporal Dead Zone (TDZ).
+// Moving the declaration before console.log fixes the error because cityOfBirth has a value before it is used.

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

@@ -1,9 +1,13 @@
 const cardNumber = 4533787178994213;
-const last4Digits = cardNumber.slice(-4);
-
-// 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?
-// Then try updating the expression last4Digits is assigned to, in order to get the correct value
+const last4Digits = cardNumber.toString().slice(-4);
+
+console.log(last4Digits);
+
+// Prediction: the code will not work because cardNumber is a number,
+// and the slice() method cannot be used directly on numbers.
+
+// Running the original code gives a TypeError because cardNumber.slice is not a function.
+// This happens because slice() is available for strings and arrays, but not for numbers.
+
+// Converting cardNumber to a string first allows slice(-4) to return the last four characters.
+// Therefore, last4Digits stores "4213".

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

@@ -1,2 +1,7 @@
-const 12HourClockTime = "8:53pm";
-const 24hourClockTime = "20:53";
+const twelveHourClockTime = "8:53pm";
+const twentyFourHourClockTime = "20:53";
+
+// The error occurs because JavaScript variable names cannot start with a number.
+// Both variable names begin with digits, so JavaScript cannot parse them as valid identifiers
+// and throws a SyntaxError.
+// Renaming the variables so they start with letters fixes the error.