Variables

A variable holds a value. That's it. That is probably the most basic concept in programming.

Generally, the name you give a variable should describe the value it contains.

var name = "Sohn Jmith";
var age = 69;

It gets a bit tricky when dealing with variations of the same concept.

const name = "Sohn Jmith";
const name2 = "Sohnny";
const nameButWithLastNameInitialed = "Sohn J.";

In that case, fight the urge keep adding numbers or adjectives. Instead, take a step back and try to come up with a new, better term for the new concept.

const name = "Sohn Jmith";
const nickname = "Sohnny";
const shortName = "Sohn J.";

Values

Try to make it easy to guess what the type of value is from the name too.

// BAD
const paid = true;
const paid2 = 1245.5;
const paid3 = "Sohn Jmith";

// GOOD
const isPaid = true;
const paymentAmount = 1245.5;
const payee = "Sohn Jmith";

TIP

For boolean variables (ie, variables that contains either true or false), prefix the variable with is, has, or should.

Constants

When you know a value will never change, it is a good idea to use a different case style for it. Generally, an upper snake case is recommended.

const WHITE_COLOR_HEX = "#000000";