- -- operator
- -= operator
- ++ operator
- += operator
- Accessing and setting content
- Array concat() method
- Array indexOf()
- Array length
- Array pop()
- Array shift
- Arrays
- Booleans
- Braces
- Callback function
- Calling the function
- Class
- Closure
- Code block
- Comment
- Conditions
- Console
- Constructor
- Creating a p element
- Data types
- Date getTime()
- Destructuring
- Else
- Else if
- Enum
- Equals operator
- Error Handling
- ES6
- Event loop
- Events
- Extend
- Fetch API
- Filter
- For loop
- forEach()
- Function
- Function bind()
- Function name
- Greater than
- Head element
- Hoisting
- If statement
- includes()
- Infinity property
- Iterator
- JSON
- Less than
- Local storage
- Map
- Methods
- Module
- Numbers
- Object.keys()
- Overriding methods
- Parameters
- Promises
- Random
- Reduce
- Regular expressions
- Removing an element
- Replace
- Scope
- Session storage
- Sort
- Splice
- String
- String concat()
- String indexOf()
- Substring
- Switch statement
- Template literals
- Ternary operator
- Title
- Type conversion
- While loop
JAVASCRIPT
JavaScript Code Block: Syntax, Usage, and Examples
A JavaScript code block is a group of one or more statements enclosed in curly braces {}
. Code blocks are used to control which pieces of code run and when, especially inside conditionals, loops, and functions.
How to Use a Code Block in JavaScript
To write a code block in JavaScript, simply wrap your statements inside {}
. This structure groups the code together and tells JavaScript to treat it as one unit.
if (true) {
console.log("I'm inside a code block!");
}
The curly braces here define the code block. Even if there's only one statement inside, using {}
clearly marks the beginning and end of that block.
You’ll see code blocks in JavaScript used in many places:
- After
if
,else if
, andelse
- In
for
,while
, anddo...while
loops - Inside functions
- Inside arrow functions with multiple statements
When to Use JavaScript Code Blocks
Code blocks aren't just decorative — they're essential for grouping logic and defining scope. Here are some common scenarios where you'll use a code block in JavaScript.
1. Conditional Logic
A code block is required if you want to execute multiple statements in an if
or else
block. Without curly braces, only the next line runs.
const age = 20;
if (age >= 18) {
console.log("You can vote.");
console.log("And get a driver's license.");
}
2. Loops
Every loop structure in JavaScript relies on a code block to know which code should repeat.
for (let i = 0; i < 3; i++) {
console.log("Loop number:", i);
}
3. Function Bodies
Functions must have a block to contain their code. Even a short function like this one uses a code block.
function greet() {
console.log("Hello!");
}
4. Arrow Functions with Multiple Lines
For arrow functions, a code block is required if you're doing more than just returning a value.
const sayHi = () => {
const name = "Tariq";
console.log(`Hi, ${name}!`);
};
Examples of JavaScript Code Blocks
Let’s look at different types of code blocks in action.
Example 1: Code Block in an If Statement
const isRaining = true;
if (isRaining) {
console.log("Take an umbrella.");
console.log("Or wear a raincoat.");
}
Without the code block, only the first line would run. The second would run regardless of the condition.
Example 2: Code Block in a Loop
let count = 0;
while (count < 2) {
console.log("Counting:", count);
count++;
}
The code block includes both console.log
and count++
, so both happen with each loop.
Example 3: Code Block in a Function
function sum(a, b) {
const result = a + b;
return result;
}
Here, the code block groups the variable declaration and the return
statement.
Example 4: Code Block in an Else Block
const isLoggedIn = false;
if (isLoggedIn) {
console.log("Welcome back!");
} else {
console.log("Please log in.");
}
The else
block runs only if the if
condition fails. The {}
ensure the right group of actions runs.
Learn More About JavaScript Code Blocks
Code Block Scope
Each JavaScript code block introduces a new block scope. This affects how variables behave. For example, let
and const
variables are only accessible inside the block where they’re declared.
{
let secret = "hidden";
console.log(secret); // works
}
console.log(secret); // ReferenceError
This concept helps prevent bugs and keeps your variables tidy.
Code Blocks vs. Single-Line Statements
JavaScript allows single-line statements without code blocks, but this can lead to problems.
if (true)
console.log("Only this runs");
console.log("This always runs"); // ⚠️ Runs regardless of the condition
Adding a code block avoids confusion:
if (true) {
console.log("Now it's clear both belong to the if!");
}
Nested Code Blocks
You can place one code block inside another. This is common in nested conditionals or loops.
for (let i = 0; i < 2; i++) {
if (i === 1) {
console.log("Nested block triggered");
}
}
Nested blocks help organize complex logic and keep related actions grouped together.
Formatting and Readability
Using code blocks consistently improves readability. Even when JavaScript doesn't require them, it's a good habit to include {}
— especially when you're working on a team or revisiting your own code later.
Sign up or download Mimo from the App Store or Google Play to enhance your programming skills and prepare for a career in tech.