Predict, explain and solve 1.js in errors

Author: habohlin

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

@@ -2,9 +2,13 @@
 
 // Why will an error occur when this program runs?
 // =============> write your prediction here
+// Answer: I will get a Syntax Error, because the variable decimalNumber is a parameter
+// of the function, and then it gets re-declared inside the function. Removing the
+// "const" would make sure it's not re-declared, just value reassigned on that line.
 
 // 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 +17,26 @@ function convertToPercentage(decimalNumber) {
 }
 
 console.log(decimalNumber);
+*/
 
 // =============> write your explanation here
+// Answer: I got SyntaxError: Identifier 'decimalNumber' has already been declared
+// I will make sure it's not re-declared in the function by removing the "const"
+
+// After removing the "const" I got a new error. ReferenceError: decimalNumber is not defined. I realized
+// that the console.log at the bottom didn't call the function but just logged decimalNumber which hadn't
+// been defined in the global scope. Putting back the "const", I will move the declaration of decimalNumber
+// to outside the function to make the scope global. Now the global decimalNumber has nothing to do with the
+// local parameter decimalNumber in the function.
 
 // Finally, correct the code to fix the problem
 // =============> write your new code here
+function convertToPercentage(decimalNumber) {
+  const percentage = `${decimalNumber * 100}%`;
+
+  return percentage;
+}
+
+const decimalNumber = 0.5;
+
+console.log(decimalNumber);