assignment in conditional expression js

How to Use the Ternary Operator in JavaScript – JS Conditional Example

The ternary operator is a helpful feature in JavaScript that allows you to write concise and readable expressions that perform conditional operations on only one line.

In this article, you will learn why you may want to use the ternary operator, and you will see an example of how to use it. You will also learn some of the best practices to keep in mind when you do use it.

Let's get into it!

What Is The Ternary Operator in JavaScript?

The ternary operator ( ?: ), also known as the conditional operator, is a shorthand way of writing conditional statements in JavaScript – you can use a ternary operator instead of an if..else statement.

A ternary operator evaluates a given condition, also known as a Boolean expression, and returns a result that depends on whether that condition evaluates to true or false .

Why Use the Ternary Operator in JavaScript?

You may want to use the ternary operator for a few reasons:

• Your code will be more concise : The ternary operator has minimal syntax. You will write short conditional statements and fewer lines of code, which makes your code easier to read and understand.
• Your code will be more readable : When writing simple conditions, the ternary operator makes your code easier to understand in comparison to an if..else statement.
• Your code will be more organized : The ternary operator will make your code more organized and easier to maintain. This comes in handy when writing multiple conditional statements. The ternary operator will reduce the amount of nesting that occurs when using if..else statements.
• It provides flexibility : The ternary operator has many use cases, some of which include: assigning a value to a variable, rendering dynamic content on a web page, handling function arguments, validating data and handling errors, and creating complex expressions.
• It enhances performance : In some cases, the ternary operator can perform better than an if..else statement because the ternary operator gets evaluated in a single step.
• It always returns a value : The ternary operator always has to return something.

How to Use the Ternary Operator in JavaScript – a Syntax Overview

The operator is called "ternary" because it is composed of three parts: one condition and two expressions.

The general syntax for the ternary operator looks something similar to the following:

Let's break it down:

• condition is the Boolean expression you want to evaluate and determine whether it is true or false . The condition is followed by a question mark, ? .
• ifTrueExpression is executed if the condition evaluates to true .
• ifFalseExpression is executed if the condition evaluates to false .
• The two expressions are separated by a colon, . .

The ternary operator always returns a value that you assign to a variable:

Next, let's look at an example of how the ternary operator works.

How to Use the Ternary Operator in JavaScript

Say that you want to check whether a user is an adult:

In this example, I used the ternary operator to determine whether a user's age is greater than or equal to 18 .

Firstly, I used the prompt() built-in JavaScript function.

This function opens a dialog box with the message What is your age? and the user can enter a value.

I store the user's input in the age variable.

Next, the condition ( age >= 18 ) gets evaluated.

If the condition is true , the first expression, You are an adult , gets executed.

Say the user enters the value 18 .

The condition age >= 18 evaluates to true :

If the condition is false , the second expression, You are not an adult yet , gets executed.

Say the user enters the value 17 .

The condition age >= 18 now evaluates to false :

As mentioned earlier, you can use the ternary operator instead of an if..else statement.

Here is how you would write the same code used in the example above using an if..else statement:

Ternary Operator Best Practices in JavaScript

Something to keep in mind when using the ternary operator is to keep it simple and don't overcomplicate it.

The main goal is for your code to be readable and easily understandable for the rest of the developers on your team.

So, consider using the ternary operator for simple statements and as a concise alternative to if..else statements that can be written in one line.

If you do too much, it can quickly become unreadable.

For example, in some cases, using nested ternary operators can make your code hard to read:

If you find yourself nesting too many ternary operators, consider using if...else statements instead.

Wrapping Up

Overall, the ternary operator is a useful feature in JavaScript as it helps make your code more readable and concise.

Use it when a conditional statement can be written on only one line and keep code readability in mind.

Thanks for reading, and happy coding! :)

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Home » JavaScript Tutorial » JavaScript Ternary Operator

JavaScript Ternary Operator

Summary : in this tutorial, you will learn how to use the JavaScript ternary operator to make your code more concise.  

Introduction to JavaScript ternary operator

When you want to execute a block if a condition evaluates to true , you often use an if…else statement. For example:

In this example, we show a message that a person can drive if the age is greater than or equal to 16. Alternatively, you can use a ternary operator instead of the if-else statement like this:

Or you can use the ternary operator in an expression as follows:

Here’s the syntax of the ternary operator:

In this syntax, the condition is an expression that evaluates to a Boolean value, either true or false .

If the condition is true , the first expression ( expresionIfTrue ) executes. If it is false, the second expression ( expressionIfFalse ) executes.

The following shows the syntax of the ternary operator used in an expression:

In this syntax, if the condition is true , the variableName will take the result of the first expression ( expressionIfTrue ) or expressionIfFalse otherwise.

JavaScript ternary operator examples

Let’s take some examples of using the ternary operator.

1) Using the JavaScript ternary operator to perform multiple statements

The following example uses the ternary operator to perform multiple operations, where each operation is separated by a comma. For example:

In this example, the returned value of the ternary operator is the last value in the comma-separated list.

2) Simplifying ternary operator example

See the following example:

If the locked is 1, then the canChange variable is set to false , otherwise, it is set to true . In this case, you can simplify it by using a Boolean expression as follows:

Description

Specifications, browser compatibility.

The conditional (ternary) operator is the only JavaScript operator that takes three operands. This operator is frequently used as a shortcut for the if statement.

The source for this interactive example is stored in a GitHub repository. If you'd like to contribute to the interactive examples project, please clone https://github.com/mdn/interactive-examples and send us a pull request.

Besides false , possible falsy expressions are:  null ,  NaN ,  0 , the empty string ( "" ), and  undefined . If condition  is any of these, the result of the conditional expression will be exprIfFalse .

A simple example:

One common usage is to handle a value that may be null :

Conditional chains

The ternary operator is right-associative, which means it can be "chained" in the following way, similar to an  if … else if … else if … else  chain:

• if statement

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Conditional Statements in JavaScript

JavaScript Conditional statements allow you to execute specific blocks of code based on conditions. If the condition meets then a particular block of action will be executed otherwise it will execute another block of action that satisfies that particular condition.

There are several methods that can be used to perform Conditional Statements in JavaScript.

• if statement : Executes a block of code if a specified condition is true.
• else statement : Executes a block of code if the same condition of the preceding if statement is false.
• else if statement : Adds more conditions to the if statement, allowing for multiple alternative conditions to be tested.
• switch statement : Evaluates an expression, then executes the case statement that matches the expression’s value.
• ternary operator (conditional operator) : Provides a concise way to write if-else statements in a single line.

JavaScript Conditional statements Examples:

1. using if statement.

The if statement is used to evaluate a particular condition. If the condition holds true, the associated code block is executed.

Example: In this example, we are using the if statement to find given number is even or odd.

Explanation: This JavaScript code determines if the variable `num` is even or odd using the modulo operator `%`. If `num` is divisible by 2 without a remainder, it logs “Given number is even number.” Otherwise, it logs “Given number is odd number.”

2. Using if-else Statement

The if-else statement will perform some action for a specific condition. Here we are using the else statement in which the else statement is written after the if statement and it has no condition in their code block.

Example: In this example, we are using if-else conditional statement to check the driving licence eligibility date.

Explanation: This JavaScript code checks if the variable `age` is greater than or equal to 18. If true, it logs “You are eligible for a driving license.” Otherwise, it logs “You are not eligible for a driving license.” This indicates eligibility for driving based on age.

3. else if Statement

The else if statement in JavaScript allows handling multiple possible conditions and outputs, evaluating more than two options based on whether the conditions are true or false.

Example: In this example, we are using the above-explained approach.

Explanation: This JavaScript code determines whether the constant `num` is positive, negative, or zero. If `num` is greater than 0, it logs “Given number is positive.” If `num` is less than 0, it logs “Given number is negative.” If neither condition is met (i.e., `num` is zero), it logs “Given number is zero.”

4. Using Switch Statement (JavaScript Switch Case)

As the number of conditions increases, you can use multiple else-if statements in JavaScript. but when we dealing with many conditions, the switch statement may be a more preferred option.

Example: In this example, we find a branch name Based on the student’s marks, this switch statement assigns a specific engineering branch to the variable Branch. The output displays the student’s branch name,

Explanation:

This JavaScript code assigns a branch of engineering to a student based on their marks. It uses a switch statement with cases for different mark ranges. The student’s branch is determined according to their marks and logged to the console.

5. Using Ternary Operator ( ?: )

The conditional operator, also referred to as the ternary operator (?:), is a shortcut for expressing conditional statements in JavaScript.

Example: In this example, we use the ternary operator to check if the user’s age is 18 or older. It prints eligibility for voting based on the condition.

Explanation: This JavaScript code checks if the variable `age` is greater than or equal to 18. If true, it assigns the string “You are eligible to vote.” to the variable `result`. Otherwise, it assigns “You are not eligible to vote.” The value of `result` is then logged to the console.

Conditional Statements in JavaScript Use-Cases:

1. javascript if-else.

JavaScript  if-else  or conditional statements will perform some action for a specific condition.

2. Control Statements in JavaScript

Control Statements are used to control the flow of the program with the help of conditional statements.

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• Assignment operators

An assignment operator assigns a value to its left operand based on the value of its right operand.

The basic assignment operator is equal ( = ), which assigns the value of its right operand to its left operand. That is, x = y assigns the value of y to x . The other assignment operators are usually shorthand for standard operations, as shown in the following definitions and examples.

Simple assignment operator which assigns a value to a variable. The assignment operation evaluates to the assigned value. Chaining the assignment operator is possible in order to assign a single value to multiple variables. See the example.

Addition assignment

The addition assignment operator adds the value of the right operand to a variable and assigns the result to the variable. The types of the two operands determine the behavior of the addition assignment operator. Addition or concatenation is possible. See the addition operator for more details.

Subtraction assignment

The subtraction assignment operator subtracts the value of the right operand from a variable and assigns the result to the variable. See the subtraction operator for more details.

Multiplication assignment

The multiplication assignment operator multiplies a variable by the value of the right operand and assigns the result to the variable. See the multiplication operator for more details.

Division assignment

The division assignment operator divides a variable by the value of the right operand and assigns the result to the variable. See the division operator for more details.

Remainder assignment

The remainder assignment operator divides a variable by the value of the right operand and assigns the remainder to the variable. See the remainder operator for more details.

Exponentiation assignment

This is an experimental technology, part of the ECMAScript 2016 (ES7) proposal. Because this technology's specification has not stabilized, check the compatibility table for usage in various browsers. Also note that the syntax and behavior of an experimental technology is subject to change in future version of browsers as the spec changes.

The exponentiation assignment operator evaluates to the result of raising first operand to the power second operand. See the exponentiation operator for more details.

Left shift assignment

The left shift assignment operator moves the specified amount of bits to the left and assigns the result to the variable. See the left shift operator for more details.

Right shift assignment

The right shift assignment operator moves the specified amount of bits to the right and assigns the result to the variable. See the right shift operator for more details.

Unsigned right shift assignment

The unsigned right shift assignment operator moves the specified amount of bits to the right and assigns the result to the variable. See the unsigned right shift operator for more details.

Bitwise AND assignment

The bitwise AND assignment operator uses the binary representation of both operands, does a bitwise AND operation on them and assigns the result to the variable. See the bitwise AND operator for more details.

Bitwise XOR assignment

The bitwise XOR assignment operator uses the binary representation of both operands, does a bitwise XOR operation on them and assigns the result to the variable. See the bitwise XOR operator for more details.

Bitwise OR assignment

The bitwise OR assignment operator uses the binary representation of both operands, does a bitwise OR operation on them and assigns the result to the variable. See the bitwise OR operator for more details.

Left operand with another assignment operator

In unusual situations, the assignment operator (e.g. x += y ) is not identical to the meaning expression (here x = x + y ). When the left operand of an assignment operator itself contains an assignment operator, the left operand is evaluated only once. For example:

Specifications

Browser compatibility.

• Arithmetic operators

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