DRY, WET, SRP, OCP, LSP, ISP, DIP, KISS, YAGNI, Fail Fast, LoD, CQS, Composition over Inheritance
1. Don’t Repeat Yourself (DRY)
This principle suggests that code should not have unnecessary duplication. Instead, it should be organized in a way that avoids redundancy and makes it easy to maintain. For example, instead of writing the same calculation in multiple places in the code, create a function that performs the calculation and call that function from the different places where the calculation is needed.
// bad example
let total = 0;
for (let i = 0; i < prices.length; i++) {
total += prices[i];
}
console.log(total);
for (let i = 0; i < prices.length; i++) {
total += prices[i];
}
console.log(total);
// good example
function calculateTotal(prices) {
let total = 0;
for (let i = 0; i < prices.length; i++) {
total += prices[i];
}
return total;
}
console.log(calculateTotal(prices));
console.log(calculateTotal(prices));2. Write Everything Twice (WET)
This is an opposite principle of DRY. It suggest that if you find yourself copy-pasting code multiple times, anticipating the identical code forking in different directions later on, having WET code may make that future change easier.
