Basics
JS Scope
Understanding JavaScript Scope
JavaScript scope includes global, local, and block, with lexical scope examples.
Introduction to JavaScript Scope
In JavaScript, scope refers to the accessibility of variables. Variables can be either globally or locally scoped. Understanding scope is crucial for effective coding, as it determines the visibility and lifetime of variables.
Global Scope
A variable declared outside any function has global scope. It is accessible from anywhere in the code after its declaration.
Local Scope
A variable declared inside a function has local scope. It is accessible only within that function.
Block Scope
With the introduction of let and const in ES6, JavaScript now supports block scope. A block is defined by curly braces {}, and variables declared with let or const inside a block are only accessible within that block.
Lexical Scope
JavaScript uses lexical scoping, meaning that the scope of a variable is determined by its location within the source code. Nested functions have access to variables declared in their outer scope.
Conclusion
Understanding scope is essential for avoiding errors and writing robust JavaScript code. By knowing how global, local, block, and lexical scope work, you can manage data visibility and lifetimes effectively.
Basics
- Introduction
- Where To
- Output
- Syntax
- Comments
- Variables
- Scope
- Hoisting
- Errors
- Data Types
- Operators
- Ternary Operator
- Short-Circuit Evaluation
- If Else
- Switch
- Loops
- For...Of/For...In
- Functions
- this Keyword
- Objects
- Arrays
- Strings
- Template Literals
- Numbers
- Number Properties
- Dates
- Math
- Booleans
- Type Conversion
- Destructuring
- Spread/Rest
- RegExp
- Strict Mode
- Modules
- Security Basics
- Debugging
- Best Practices
- Mistakes
- Performance
- Reserved Words
- Sets
- Maps
- Bitwise
- Array Const
