How to Use Conditional Logic with If Statements in JavaScript

JavaScript has a few different ways to use conditional logic, but the most common is the if statement. Here’s the basic syntax:

if (condition) {
  // code to run if condition is true
}

The condition is a boolean expression that will be evaluated as either true or false. If the condition is true, the code inside the curly braces will run. If it’s false, the code will be skipped.

You can also include an else statement to run code if the condition is false:

if (condition) {
  // code to run if condition is true
} else {
  // code to run if condition is false
}

You can also chain multiple conditions using else if:

if (condition1) {
  // code to run if condition1 is true
} else if (condition2) {
  // code to run if condition1 is false and condition2 is true
} else {
  // code to run if condition1 and condition2 are false
}

It’s important to note that JavaScript only runs the first block of code that evaluates to true, and ignore the rest.

if (condition1) {
  // code to run if condition1 is true
} 
if (condition2) {
  // code to run if condition2 is true
}

This will run both the code block regardless of the condition1 or condition2 is true or false.

Here’s an example of using a conditional statement to check if a number is even or odd:

let num = 5;
if (num % 2 == 0) {
  console.log(num + " is even");
} else {
  console.log(num + " is odd");
}

This would output “5 is odd” to the console.

You can also use comparison operators in your conditions, such as >, <, >=, <=, ==, and !=. These can be used to compare variables and values. For example:

let x = 5;
let y = 10;
if (x < y) {
  console.log(x + " is less than " + y);
}

This would output “5 is less than 10” to the console.

You can also use logical operators in your conditions, such as && (and), || (or), and ! (not). These can be used to combine multiple conditions or negate a condition. For example:

let x = 5;
let y = 10;
let z = 15;
if (x < y && x < z) {
  console.log(x + " is the smallest number");
}

This would output “5 is the smallest number” to the console, because x < y and x < z are both true.

You can also use the ternary operator as a shorthand for an if-else statement. The ternary operator has the following syntax:

(condition) ? statement1 : statement2;

For example:

let age = 25;
let canDrink = (age >= 21) ? "can drink" : "cannot drink";
console.log(canDrink);

This would output “can drink” to the console because age is greater than 21.

It’s important to use proper indentation and formatting when working with conditional statements, as it can make your code much easier to read and understand.

In conclusion, if statements, else statement, else if statement, comparison operators, logical operators and ternary operator are the ways to use conditional logic in JavaScript. These are fundamental concepts that are used to control the flow of a program and make decisions based on the values of variables.