Comparison and logical operators — Operators and coercion

Comparison operators

Every "if this happens, do that" starts with a comparison. Here you build the yes/no questions that will later make decisions for you.

They compare two values and always return a boolean (true or false).

Operator	Meaning	Example	Result
`===`	Strictly equal	`3 === 3`	`true`
`!==`	Strictly different	`3 !== 4`	`true`
`<`	Less than	`3 < 4`	`true`
`>`	Greater than	`3 > 4`	`false`
`<=`	Less than or equal	`3 <= 3`	`true`
`>=`	Greater than or equal	`4 >= 5`	`false`

Remember: = assigns a value, whereas === compares. Confusing them is one of the most typical mistakes when starting out.

Logical operators

They are used to combine several conditions.

&& (AND): true only if both sides are true.
|| (OR): true if at least one is true.
! (NOT): inverts the value: !true is false.

const age = 20;
const hasTicket = true;

console.log(age >= 18 && hasTicket); // true: meets both
console.log(age < 18 || hasTicket);  // true: meets one
console.log(!hasTicket);             // false

Analogy

Imagine entry to a concert:

With && you need to be of legal age AND have a ticket. Fail either one and you don't get in.
With || they let you in if you are VIP OR you have an invitation. One is enough.

You can now compare with confidence... as long as the types match. In the next lesson coercion enters the scene, and that's where JavaScript gets mischievous. Hold on tight.

Examples

Comparisons return booleans

const grade = 7;
console.log("passes:", grade >= 5);
console.log("outstanding:", grade >= 9);

Combine conditions

const age = 20;
const license = true;
const canDrive = age >= 18 && license;
console.log("can drive:", canDrive);