Beyond labeling, good code will leverage the strength of its programming language to avoid performing the same tasks

Take a look at the following code:

const addFive = number => {
  const fiveAdded = number + 5;
  console.log(`Your number plus 5 is ${fiveAdded}`);
}

const addTen = number => {
  const tenAdded = number + 10;
  console.log(`Your number plus 10 is ${tenAdded}`);
}

const addTwenty = number => {
  const twentyAdded = number + 20;
  console.log(`Your number plus 20 is ${twentyAdded}`);
}

While these three function definitions are not exact duplicates of each other, a well-designed application will be flexible enough to join similar functionality in a single element.

const addNumber = (number, addend) => {
  const numAdded = number + addend;
  console.log(`Your number plus ${addend} is ${numAdded}`);
}

As you can see, by adding an argument to the earlier functions we can simplify our application code which will ultimately save time should we realize that we also want an addFifty() function and an addHundred() function.

Code that performs the same task in multiple places is repetitive, and the quality coder’s credo is “Don’t Repeat Yourself” (DRY). If a program performs similar tasks without refactoring into a function, it is said to “violate DRY”. “Violating DRY” is a programmer’s way of complaining: “This script is saying the same thing over and over! We can do the same thing with less code!” Let’s try to not repeat ourselves in this codebase by repurposing some of the more glaringly repeated code into functions we can call instead.