JavaScript Comparison

Comparison and logical operators are used to test true Or false.

Comparison operators

Comparison operators are used in logical statements to determine whether variables or values are equal.

Given x = 5, the following table explains the comparison operators:

Operator Description Comparison Return Test
== Equal to x == 8 false Try It
x == 5 true Try It
x == "5" true Try It
=== Values are equal and types are equal x === 5 true Try It
x === "5" false Try It
!= Not equal x != 8 true Try It
!== Values are not equal or types are not equal x !== 5 false Try It
x !== "5" true Try It
x !== 8 true Try It
> Greater than x > 8 false Try It
< Less than x < 8 true Try It
>= Greater than or equal to x >= 8 false Try It
<= Less than or equal to x <= 8 true Try It

How to use

Comparison operators can be used in conditional statements to compare values and take actions based on the results:

if (age < 18) text = "too young";

In the following chapters of this tutorial, you will learn more about conditional statements.

Logical operators

Logical operators are used to determine the logic between variables or values.

Given x = 6 and y = 3, the following table explains the logical operators:

Operator Description Example Test
&& And (x < 10 && y > 1) is true Try It
|| Or (x == 5 || y == 5) is false Try It
! Not !(x == y) is true Try It

Conditional (ternary) operator

JavaScript also includes a conditional operator that can assign a value to a variable based on certain conditions.

Syntax

variablename = (condition) ? value1:value2

Example

var voteable = (age < 18) ? "too young" : "sufficiently mature";

Try It Yourself

If the value of the variable age is less than 18, the value of the variable voteable will be "too young", otherwise the value of the variable voteable will be "sufficiently mature".

Comparing different types

Comparing different types of data may result in unpredictable outcomes.

If a string is compared with a number, JavaScript will convert the string to a number when making the comparison. An empty string will be converted to 0. A non-numeric string will be converted to always be false of NaN.

Case Value Test
2 < 12 true Try It
2 < "12" true Try It
2 < "Bill" false Try It
2 > "Bill" false Try It
2 == "Bill" false Try It
"2" < "12" false Try It
"2" > "12" true Try It
"2" == "12" false Try It

When comparing two strings, "2" is greater than "12" because (in alphabetical order) 1 is less than 2.

To ensure correct results, the variable should be converted to the appropriate type before comparison:

age = Number(age);
if (isNaN(age)) {
    voteable = "Input Error";
}
    voteable = (age < 18) ? "Too Young" : "Sufficiently Mature";
}

Try It Yourself