If-Else Statements in JavaScript
If-else statements are fundamental control flow structures in JavaScript that allow you to execute different blocks of code based on certain conditions. Mastering if-else statements is essential for writing flexible and dynamic JavaScript programs. In this chapter, we'll explore if-else statements from basic usage to more advanced techniques, covering everything you need to know to effectively use them in your code.
Basic If Statement
The basic if statement allows you to execute a block of code if a specified condition evaluates to true.
const num = 10;
if (num > 5) {
console.log("Number is greater than 5");
}
In this example, the console will log “Number is greater than 5” because the condition num > 5 evaluates to true.
If-Else Statement
The if-else statement allows you to execute one block of code if the condition is true and another block if the condition is false.
const num = 3;
if (num > 5) {
console.log("Number is greater than 5");
} else {
console.log("Number is less than or equal to 5");
}
In this example, since num is less than 5, the second block of code will be executed, and the console will log “Number is less than or equal to 5”.
Else-If Statement
The else-if statement allows you to check multiple conditions sequentially.
const num = 3;
if (num > 5) {
console.log("Number is greater than 5");
} else if (num === 5) {
console.log("Number is equal to 5");
} else {
console.log("Number is less than 5");
}
In this example, the condition num > 5 is false, so it moves to the next condition. Since num is not equal to 5 either, the last block of code will be executed, and the console will log “Number is less than 5”.
Nested If-Else Statements
You can also nest if-else statements within each other to handle more complex logic.
const num = 10;
if (num > 5) {
if (num < 15) {
console.log("Number is between 5 and 15");
} else {
console.log("Number is greater than or equal to 15");
}
} else {
console.log("Number is less than or equal to 5");
}
In this example, the condition num > 5 is false, so it moves to the next condition. Since num is not equal to 5 either, the last block of code will be executed, and the console will log “Number is less than 5”.
Ternary Operator
The ternary operator is a concise way to write if-else statements in a single line.
const num = 10;
const message = num > 5 ? "Number is greater than 5" : "Number is less than or equal to 5";
console.log(message);
- We declare a variable
numand assign it the value10. - We use the ternary operator (
? :) to assign a value to the variablemessagebased on a condition. - The condition
num > 5is evaluated. If it’s true, the expression before the:is executed, and if it’s false, the expression after the:is executed. - If
numis greater than 5, the value"Number is greater than 5"is assigned tomessage, otherwise"Number is less than or equal to 5"is assigned. - Finally, we log the value of
messageto the console.
If-else statements are essential for controlling the flow of execution in JavaScript programs. By mastering if-else statements and understanding their various forms, you'll be able to write code that handles different scenarios and conditions effectively. Experiment with different if-else structures and logical combinations to deepen your understanding and proficiency. With practice and exploration, you'll become adept at using if-else statements to create robust and flexible JavaScript applications. Happy coding !❤️