JS Comparison

Comparison Operators

Comparison operators are utilized in logical statements to assess the equality or difference between variables or values.

With x = 5, the table below outlines the comparison operators:

Operator	Description	Comparing	Returns
==	equal to	x == 8	false
		x == 5	true
		x == “5”	true
===	equal value and equal type	x === 5	true
===	equal value and equal type	x === “5”	False
!=	not equal	x != 8	True
!==	not equal value or not equal type	x !== 5	False
		x !== “5”	True
		x !== 8	True
>	greater than	x > 8	False
<	less than	x < 8	True
>=	greater than or equal to	x >= 8	False
<=	less than or equal to	x <= 8	True

How Can it be Used

Comparison operators can be employed in conditional statements to compare values and perform actions based on the outcome.

if (age < 18) text = “Too young to buy alcohol”;

Logical Operators

Logical operators are used to evaluate the relationship between variables or values.

With x = 6 and y = 3, the table below describes the logical operators:

Operator	Description	Example
&&	and	(x < 10 && y > 1) is true
\|\|	or	(x == 5 \|\| y == 5) is false
!	not	!(x == y) is true

Conditional (Ternary) Operator

JavaScript includes a conditional operator that assigns a value to a variable based on a specified condition.

Syntax

variablename = (condition) ? value1:value2

Example

let voteable = (age < 18) ? “Too young”:“Old enough”;

If the variable age is less than 18, the variable voteable will be assigned the value “Too young”; otherwise, it will be “Old enough.”

Comparing Different Types

Comparing data of different types can lead to unexpected results.

When comparing a string with a number, JavaScript converts the string to a number for the comparison. An empty string is converted to 0, while a non-numeric string is converted to NaN, which is always treated as false.

Case	Value
2 < 12	true
2 < “12”	true
2 < “John”	false
2 > “John”	false
2 == “John”	false
“2” < “12”	false
“2” > “12”	true
“2” == “12”	false

When comparing two strings, “2” is considered greater than “12” because, in alphabetical order, 1 comes before 2.

To ensure accurate results, variables should be converted to the appropriate type before comparison.

age = Number(age);
if (isNaN(age)) {
voteable = “Input is not a number”;
} else {
voteable = (age < 18) ? “Too young” : “Old enough”;
}