DRY is an abbreviation for Don't Repeat Yourself .

WRONG: It doesn't mean to not repeat code.

CORRECT: Don't repeat business logic. Meaning to not repeat code that has an specific objective.

A good way to look at it is, if you are coding the same behavior more the 3 times then perhaps you should move that to abstract that code.

KISS is an abbreviation for Keep It Simple and Stupid .

It means to keep you code easy to ready and understand for someone that never seen it before, keeping you parameter, const, variables with readable names.

WRONG:

function showUsersInformation(data) {
	return data.map(u => {
		name: u.name,
		age: u.age
	}
}

CORRECT:

function getUsersNameAndAge(users) {
	return users.map(user => {
		name: user.name,
		age: user.age
	}
}

YAGNI is an abbreviation for You Ain't Gonna Need It .

It means to not implement tools and features just for the sake of implementing it, over complicating your application before you actually need to implement those tools or features.