What is Hard Coding and Why We Should Avoid It

Hard coding means putting specific numbers or values directly into your code instead of using variables, constants, or getting them from outside sources.

This makes the code less flexible because if you need to change those numbers, you have to go into the code and update them everywhere they are used.

Let me illustrate this with a simple example. Suppose you're creating a shopping cart system that applies a constant discount to the total price:

function calculateTotalPrice(items) {
  let totalPrice = 0;

  for (let i = 0; i < items.length; i++) {
    totalPrice += items[i].price;
  }

  // Hardcoded discount applied at multiple places
  const discount = 0.1; // 10% discount
  totalPrice -= totalPrice * discount; // Applying discount here
  return totalPrice;
}

function displayFinalPrice(items) {
  let totalPrice = 0;

  for (let i = 0; i < items.length; i++) {
    totalPrice += items[i].price;
  }

  // Hardcoded discount applied again
  const discount = 0.1; // 10% discount
  totalPrice -= totalPrice * discount; // Applying discount here
  console.log("Final Price: $" + totalPrice.toFixed(2));
}

In this example, the discount rate (0.10) is hardcoded in two places: calculateTotalPrice and displayFinalPrice. If you need to change the discount to 0.15, you would have to update it in both locations. If you forget to update one, your application might behave inconsistently.

A better approach is to define such values as constants or variables. Here’s how you can refactor the code:

const DISCOUNT_RATE = 0.1; // 10% discount

function calculateTotalPrice(items) {
  let totalPrice = 0;

  for (let i = 0; i < items.length; i++) {
    totalPrice += items[i].price;
  }

  // Using the constant for discount
  totalPrice -= totalPrice * DISCOUNT_RATE;
  return totalPrice;
}

function displayFinalPrice(items) {
  let totalPrice = 0;

  for (let i = 0; i < items.length; i++) {
    totalPrice += items[i].price;
  }

  // Using the constant for discount
  totalPrice -= totalPrice * DISCOUNT_RATE;
  console.log("Final Price: $" + totalPrice.toFixed(2));
}

By using a constant like DISCOUNT_RATE, you only need to update the discount rate in one place. This approach ensures that all parts of your code use the same value, preventing inconsistencies.

Additionally, using descriptive names for constants, like DISCOUNT_RATE, enhances code readability and makes it clear what the value represents.

Avoiding hardcoded values and using well-named variables or constants will make your code more flexible, readable, and less error-prone.