question answered

Author: pathywang

Sprint-1/3-mandatory-interpret/1-percentage-change.js

@@ -20,3 +20,35 @@ 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: There are three function calls, which are: Number(...), replaceAll(...) and console.log(...)
+//   Function call lines: 1. carPrice = Number(carPrice.replaceAll(",", ""));
+//                        2. priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," ""));
+//                        3. console.log(`The percentage change is ${percentageChange}`);
+
+//b: priceAfterOneYear = Number(priceAfterOneYear.replaceAll("," "")) has an error,SyntaxError: Unexpected string
+//    missing a comma between the arguments of replaceAll.
+//    correct is: priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",",""));
+
+// c: two reassignment statements: 1.carPrice = Number(carPrice.replaceAll(",", ""));
+//                               2.priceAfterOneYear = Number(priceAfterOneYear.replaceAll(",", ""));
+
+// d: four variable declarations(using let or cost to declare new variables):
+//    1. let carPrice = "10,000";
+//    2. let priceAfterOneYear = "8,543";
+//    3. const priceDifference = carPrice - priceAfterOneYear;
+//    4.const percentageChange = (priceDifference / carPrice) * 100;
+
+//e:   1.carPrice is a string like "10,000"
+//     2.replaceAll(",", "") removes commas → becomes "10000"
+//     3.Number(...) converts the string "10000" into the number 10000
+//     The purpose is to convert a currency string with commas (e.g., "10,000") into a usable number (10000) for math calculations.
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