Learn Local Variables in Practice | Working with Function Data and Scope

Local variables are essential for keeping your JavaScript code organized and safe from unexpected bugs. When you declare a variable inside a function using the let or const keyword, that variable is only accessible within that function. This means you can use the same variable names in different functions without them interfering with each other. More importantly, local variables protect your global data from being accidentally changed by code inside a function. If you always use local variables for temporary calculations or intermediate results, you avoid situations where a function might overwrite or modify a variable that other parts of your code depend on. This isolation is a key reason why local variables are considered a best practice in JavaScript programming.


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let total = 100;

function addTax(amount) {
  let taxRate = 0.08;
  let taxedAmount = amount + amount * taxRate;
  return taxedAmount;
}

let priceWithTax = addTax(total);

console.log("Global total is still:", total);
console.log("Price with tax is:", priceWithTax);

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 4

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              123456789101112
            
let total = 100;

function addTax(amount) {
  let taxRate = 0.08;
  let taxedAmount = amount + amount * taxRate;
  return taxedAmount;
}

let priceWithTax = addTax(total);

console.log("Global total is still:", total);
console.log("Price with tax is:", priceWithTax);

Everything was clear?

Thanks for your feedback!

Section 2. Chapter 4