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JavaScript Booleans
A JavaScript Boolean represents one of two values: true or false.
Boolean Values
Very often, in programming, you will need a data type that can only have one of two values, like
- YES / NO
- ON / OFF
- TRUE / FALSE
For this, JavaScript has a Boolean data type. It can only take the values true or false.
The Boolean() Function
You can use the Boolean() function to find out if an
expression (or a variable) is
true:
Example
Boolean(10 > 9)
//
returns true
Or even easier:
Example
(10 > 9)
// also returns
true
10 > 9
// also returns true
Comparisons and Conditions
The chapter JS Comparisons gives a full overview of comparison operators.
The chapter JS Conditions gives a full overview of conditional statements.
Here are some examples:
| Operator | Description | Example |
|---|---|---|
| == | equal to | if (day == "Monday") |
| > | greater than | if (salary > 9000) |
| < | less than | if (age < 18) |
The Boolean value of an expression is the basis for all JavaScript comparisons and conditions.
Everything With a "Value" is True
Examples
100
3.14
-15
"Hello"
"false"
7 + 1 + 3.14
Everything Without a "Value" is False
The Boolean value of 0 (zero) is false:
let x = 0;
Boolean(x); // returns false