Complete Sprint-3 errors exercise (0.js, 1.js, 2.js)

Author: lwandogwele52-ui

Sprint-3/1-key-errors/0.js

@@ -1,13 +1,24 @@
 // Predict and explain first...
-//  =============> write your prediction here
+//  ==============> write your prediction here
+// I predict this will throw a SyntaxError, because the parameter 'str' is
+// being redeclared with 'let' inside the function.
 
 // 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;
+  let result = `${str[0].toUpperCase()}${str.slice(1)}`;
+  return result;
 }
 
-// =============> write your explanation here
-// =============> write your new code here
+console.log(capitalise("hello"));
+
+// ==============> write your explanation here
+// The parameter 'str' already existed in the function's scope. The original
+// code tried to declare another variable with 'let str', which caused a
+// naming collision — JavaScript doesn't allow redeclaring a variable with
+// 'let' in the same scope. This threw a SyntaxError before the function
+// could even run. Renaming the new variable to 'result' fixes the collision.
+
+// ==============> write your new code here
+// (the fixed function above already satisfies this)

Sprint-3/1-key-errors/1.js

@@ -1,20 +1,33 @@
 // Predict and explain first...
-
 // Why will an error occur when this program runs?
-// =============> write your prediction here
+//  ==============> write your prediction here
+// I predict this will throw a SyntaxError, because 'decimalNumber' is being
+// redeclared with 'const' inside the function, even though it's already the
+// function's parameter.
 
 // Try playing computer with the example to work out what is going on
 
 function convertToPercentage(decimalNumber) {
-  const decimalNumber = 0.5;
   const percentage = `${decimalNumber * 100}%`;
 
   return percentage;
 }
 
-console.log(decimalNumber);
+console.log(convertToPercentage(0.5));
 
-// =============> write your explanation here
+// ==============> write your explanation here
+// 'decimalNumber' was already declared as the function's parameter. The
+// original code tried to declare another variable with the same name using
+// 'const decimalNumber = 0.5;', which caused a naming collision — JavaScript
+// doesn't allow redeclaring a variable in the same scope. This threw a
+// SyntaxError before the function could run.
+//
+// There was also a second issue: the original 'console.log(decimalNumber);'
+// was outside the function, so 'decimalNumber' didn't exist there (it's
+// scoped only inside 'convertToPercentage'), and the function was never
+// actually called. The fix removes the duplicate declaration and calls
+// convertToPercentage(0.5) directly, logging its return value instead.
 
 // Finally, correct the code to fix the problem
-// =============> write your new code here
+// ==============> write your new code here
+// (the fixed function above already satisfies this)

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

@@ -1,20 +1,31 @@
-
 // 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
+// this function should square any number but instead we're getting an error
+//  ==============> write your prediction of the error here
+// I predict this will throw a SyntaxError, because '3' is used as the
+// parameter name in 'function square(3)', and a number can't be used as a
+// parameter name — parameter names must be valid identifiers (like variable
+// names).
 
-function square(3) {
-    return num * num;
+function square(num) {
+  return num * num;
 }
 
-// =============> write the error message here
-
-// =============> explain this error message here
+console.log(square(3));
 
-// Finally, correct the code to fix the problem
-
-// =============> write your new code here
+// ==============> write the error message here
+// SyntaxError: Unexpected number
 
+// ==============> explain this error message here
+// Function parameters must be valid identifiers — the same rules as variable
+// names (they must start with a letter, '$', or '_', never a digit). The
+// original code used '3' as the parameter name, which isn't a valid
+// identifier, so JavaScript couldn't even parse the function definition.
+// This error happens before any code runs. There was also a second bug: the
+// function body referred to 'num', which didn't match the (invalid)
+// parameter name at all — fixing the parameter name to 'num' resolves both
+// issues at once.
 
+// Finally, correct the code to fix the problem
+// ==============> write your new code here
+// (the fixed function above already satisfies this)