- Trending Categories
Data Structure
Networking
RDBMS
Operating System
Java
MS Excel
iOS
HTML
CSS
Android
Python
C Programming
C++
C#
MongoDB
MySQL
Javascript
PHP
Physics
Chemistry
Biology
Mathematics
English
Economics
Psychology
Social Studies
Fashion Studies
Legal Studies
- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who
Block Scoping in JavaScript.
Block scope is an area between two { curly braces } which can be between loops, if condition or switch statement. The let and const introduced in ES2015 allow us to create block scoped variables that can be accessed only inside those block.
Following is the code showing block scoping in JavaScript −
Example
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8" />
<meta name="viewport" content="width=device-width, initial-scale=1.0" />
<title>Document</title>
<style>
body {
font-family: "Segoe UI", Tahoma, Geneva, Verdana, sans-serif;
}
.result{
font-size: 20px;
font-weight: 500;
}
</style>
</head>
<body>
<h1>Block scoping in JavaScript</h1>
<div style="color: green;" class="result"></div>
<button class="Btn">CLICK HERE</button>
<h3>Click on the above button to access variable inside and outside the block</h3>
<script>
let resEle = document.querySelector(".result");
document.querySelector(".Btn").addEventListener("click", () => {
let b = 44;{
let a = 22;
}
resEle.innerHTML = 'Accessing variable inside its block b = ' + b + '<br>';
try{
a
}
catch(err){
resEle.innerHTML += 'Accessing variable outside its block a = ' + err;
}
});
</script>
</body>
</html>Output
The above code will produce the following output −
On clicking the ‘CLICK HERE’ button −
Updated on: 16-Jul-2020
197 Views
Advertisements