The if statement

Learn how to check a condition with if.

The if statement

To run a block of code when a condition is true you use the if statement. The form is if (condition) { ... }. The condition goes inside parentheses, the code to run inside curly braces.

For example if (age >= 18) { console.log("Adult"); } prints "Adult" when age is 18 or more; otherwise it does nothing. The condition is any expression that yields true or false. Comparison operators (>, <, ==, >=, <=) are the most common ones.

Comparison operators

Condition expressions use comparison operators. === tests equal value and same type; !== means not equal or different type. > is greater than, < is less than, >= is greater or equal, <= is less or equal.

In Node.js === (three equals) is preferred; == (two equals) does type coercion and can lead to surprising results. For example 5 === "5" is false but 5 == "5" is true. Using === for type-safe comparison is a good habit.

Exercise Check the age

The age variable is set to 20. Write an if statement: when the condition age >= 18 holds, call console.log("Adult"). The output on a single line must be Adult.

Show example solution

const age = 20;
if (age >= 18) {
    console.log("Adult");
}

Test yourself

What does if (5 > 3) { console.log("yes"); } print?
```
if (5 > 3) { console.log("yes"); }
```
- yes
- nothing
- false
- 5 3
Show answer

yes — The condition 5 > 3 is true; "yes" is printed.

Write the if condition

const age = 20;
____ (age >= 18) {
    console.log("Adult");
}

Show answer

const age = 20;
if (age >= 18) {
    console.log("Adult");
}

Match each operator to its meaning

===

Equal and same type
!==

Not equal
>

Greater than
<=

Less or equal

Next lesson: else and else if

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