Relational and logical operators

Programs do not only run statements in order. They often need to check whether a condition is true, then choose what to do next. A condition usually produces a Boolean value: true or false.

Relational operators

Relational operators compare two values. The result of a comparison is a Boolean value, not another number.

Common JavaScript relational operators:

• <: less than
• >: greater than
• <=: less than or equal to
• >=: greater than or equal to
• ===: equal to
• !==: not equal to

Important: one equals sign = means assignment. Two equals signs === mean comparison.

let age = 17;

console.log(age < 18) // true;
console.log(age === 18) // false;
console.log(age !== 18) // true;

age = 17 stores 17 in the variable age. age === 18 checks whether the current value of age equals 18.

Logical operators

Logical operators combine multiple conditions. Their result is still a Boolean value.

• &&: the whole expression is true only when every condition is true.
• ||: the whole expression is true when at least one condition is true.
• !: turns true into false, and false into true.

let age = 20;
let hasTicket = true;

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

It helps to read conditions like plain language: age >= 18 && hasTicket means “the age is at least 18, and the person has a ticket.”

Combining conditions

JavaScript combines range checks with &&. Write both comparisons explicitly:

let age = 16;
console.log(age > 0 && age < 18) // true;

This is equivalent to:

console.log(age > 0 && age < 18);

When a condition becomes complex, use parentheses or meaningful variable names to keep the logic readable.

let score = 85;
let attendance = 92;

let passed = score >= 60 && attendance >= 80;
let excellent = score >= 90 || attendance >= 95;

console.log(passed) // true;
console.log(excellent) // false;

Do not rush to squeeze every condition into one line. Naming smaller conditions makes the program easier to read and debug.