Fix syntax errors and improve function implementations in key error examples

Author: Baba05206

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

@@ -3,11 +3,19 @@
 
 // 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;
 }
-
+*/
 // =============> write your explanation here
+/*Undeclared variables are automatically declared when first used. As a parameter in the 'capitalise' function,
+ 'str' is already declared. trying to declare it again with 'let' will cause a syntax error.
+*/
 // =============> write your new code here
+function capitalise(str) {
+  str = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return str;
+}
+console.log(capitalise("hello world")); // This line is inserted only to test the code. It returns "Hello world"

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

@@ -4,7 +4,7 @@
 // =============> write your prediction here
 
 // Try playing computer with the example to work out what is going on
-
+/*
 function convertToPercentage(decimalNumber) {
   const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
@@ -13,8 +13,20 @@ function convertToPercentage(decimalNumber) {
 }
 
 console.log(decimalNumber);
-
+*/
 // =============> write your explanation here
-
+/*
+1. Undeclared variables are automatically declared when first used. As a parameter in the 'convertToPercentage' function,
+'decimalNumber' is (automatically) already declared. trying to declare it again with 'const' causes a syntax error.
+2. Also, the 'console.log(decimalNumber);' line is outside the function, so 'decimalNumber' is not defined in that scope.
+3 decimalNumber = 0.5; overwrites the argument supplied, and so to make the function work as intended, this line should be removed, so the function does not ignore its input argument.
+*/
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+
+  return percentage;
+}
+
+console.log(convertToPercentage(0.25)); // This line is inserted only to test the code. It returns "25%"

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

@@ -1,20 +1,26 @@
-
 // Predict and explain first BEFORE you run any code...
 
 // this function should square any number but instead we're going to get an error
 
 // =============> write your prediction of the error here
-
+/*
 function square(3) {
     return num * num;
 }
-
+*/
 // =============> write the error message here
-
+// SyntaxError: Unexpected number
 // =============> explain this error message here
+/*
+1-The parameter name '3' is not a valid identifier. Function parameters names must (be valid variable names & not literal values), i.e. start with a letter, underscore (_), or dollar sign ($), and cannot be a number.
+2-Also, the function uses 'num' which is not defined anywhere. It should use the parameter name instead.
+3-Finally, the function is not called anywhere, so it won't produce any output.
+*/
 
 // Finally, correct the code to fix the problem
 
 // =============> write your new code here
-
-
+function square(num) {
+  return num * num;
+}
+console.log(square(3)); // This line is inserted only to test the function. It returns 9