JavaScript Comparison

Comparison Operators

Comparison operators are used in logical statements to determine equality or difference between variables or values.

Given that x = 5, the table below explains the comparison operators:

How Can it be Used

Comparison operators can be used in conditional statements to compare values and take action depending on the result:

if (age < 18) text = "Too young";

Logical Operators

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

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

Conditional (Ternary) Operator

JavaScript also contains a conditional operator that assigns a value to a variable based on some condition.

Syntax

variablename = (condition) ? value1:value2

var voteable = (age < 18) ? "Too young":"Old enough";

Comparing Different Types

Comparing data of different types may give unexpected results.

When comparing a string with a number, JavaScript will convert the string to a number when doing the comparison. An empty string converts to 0. A non-numeric string converts to NaN which is always false.

Example :

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