'if', 'if-else', 'if-else if' statements

-

Introduction

In JavaScript, conditional statements are used to perform different actions based on different conditions. These statements allow the program to make decisions and execute different code blocks based on the outcome of those decisions. There are three main types of conditional statements in JavaScript: `if`, `if else`, and `if else if`.

The `if` Statement

The `if` statement is used to execute a block of code if a specified condition is true. Here is the syntax for the `if` statement:

if (condition) {
  // code to be executed if the condition is true
} 

The `condition` can be any JavaScript expression that returns a boolean value (`true` or `false`). If the condition evaluates to `true`, the code block within the curly braces will be executed. Otherwise, the code block will be skipped.

Example:

let age = 18;
 
if (age >= 18) {
  console.log("You are old enough to vote");
}

In this example, if the `age` variable is greater than or equal to 18, the message "You are old enough to vote" will be printed to the console.

The `if else` Statement

The `if else` statement allows you to execute different code blocks based on the outcome of a condition. If the condition specified in the `if` statement evaluates to `true`, the code block within the `if` block will be executed. Otherwise, the code block within the `else` block will be executed. Here is the syntax for the `if else` statement:

if (condition) {
  // code to be executed if the condition is true
} else {
  // code to be executed if the condition is false
}

Example:

let age = 16;
 
if (age >= 18) {
  console.log("You are old enough to vote");
} else {
  console.log("You are too young to vote");
}

In this example, if the `age` variable is greater than or equal to 18, the message "You are old enough to vote" will be printed to the console. Otherwise, the message "You are too young to vote" will be printed.

The `if else if` Statement

The `if else if` statement allows you to test multiple conditions and execute different code blocks based on the outcome of those conditions. You can have any number of `else if` blocks between the `if` and `else` blocks. Here is the syntax for the `if else if` statement:

if (condition1) {
  // code to be executed if condition1 is true
} else if (condition2) {
  // code to be executed if condition2 is true
} else {
  // code to be executed if none of the conditions are true
}

The conditions are evaluated in order. If the first condition (`condition1`) is true, the code block within its associated block will be executed. If `condition1` is false, but `condition2` is true, the code block within the `else if` block will be executed. If none of the conditions are true, the code block within the `else` block will be executed.

Example:

let grade = 75;
 
if (grade >= 90) {
  console.log("You got an A");
} else if (grade >= 80) {
  console.log("You got a B");
} else if (grade >= 70) {
  console.log("You got a C");
} else {
  console.log("You got an F");
}

In this example, depending on the value of the `grade` variable, a different message will be printed to the console. If the `grade` is 75, the message "You got a C" will be printed.

Key Takeaways

  • Conditional statements in JavaScript allow you to make decisions and execute different code blocks based on conditions.

  • The `if` statement is used to execute a code block if a condition is true.

  • The `if else` statement is used to execute one code block if a condition is true, and another code block if the condition is false.

  • The `if else if` statement allows you to test multiple conditions and execute different code blocks based on the outcome of those conditions.

Comments

Post a Comment

Popular posts from this blog

Limitations of JavaScript

-
Introduction to Limitations of JavaScript JavaScript is a widely used programming language that runs on all major web browsers. It is known for its versatility and ability to create dynamic and interactive web pages. However, like any programming language, JavaScript has its limitations. In this learning guide, we will explore the limitations of JavaScript to help you better understand its strengths and weaknesses. 1. Performance Limitations JavaScript is an interpreted language , which means that it is executed line by line at run-time. This can result in slower performance compared to compiled languages like C++ or Java. Additionally, JavaScript is a single-threaded language , meaning that it can only execute one operation at a time. This can lead to performance bottlenecks when dealing with computationally intensive tasks or handling large amounts of data. // Example of slow performance in JavaScript for ( var i = 0 ; i < 1000000000 ; i ++ ) { // Perform some computati...
Read more

'for in' Loop

-
Introduction to JavaScript 'for in' Loop The `for in` loop is a type of loop in JavaScript that is used to iterate over the properties of an object. It is often used when you need to loop through the keys or properties of an object and perform some action on each one. Unlike other loops like `for` and `while`, the `for in` loop is specifically designed to work with objects. Syntax The syntax for the `for in` loop is as follows: for   ( variable  in  object )   {    // code to be executed } The `variable` represents a temporary variable that will hold the key of each property in the object. The `object` is the object that you want to iterate over. Example Let's take a look at an example to understand how the `for in` loop works: const  person  =   {   name :   'John' ,   age :   30 ,   gender :   'male' } ;   for ...
Read more

What is JIT compiler? Is JavaScript compiled or interpreted or both?

-
What is JIT compiler? A Just-In-Time (JIT) compiler is a type of compiler that dynamically converts programming code into machine code at runtime, just before the code is executed. Unlike traditional compilers that convert the entire program ahead of time, a JIT compiler optimizes and compiles code on-the-fly, as it is needed. The primary advantage of a JIT compiler is that it can make the execution of code significantly faster compared to an interpreter. It achieves this by analyzing the code at runtime, identifying hotspots (frequently executed portions of code), and applying various optimization techniques to generate highly efficient machine code specific to the underlying hardware. JIT compilers are commonly used in programming languages such as Java and JavaScript, where the execution speed of the code is crucial. So is JavaScript Compiled or Interpreted? JavaScript is generally considered an interpreted language . Traditionally, JavaScript code is executed by an interpreter, wh...
Read more