In JavaScript, variables are like containers that store data. There are three ways to create (or declare) these containers: var, let, and const.
Let’s look at what makes them different! 🌟
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var– The Old-School Way 📜
Scope: var works within the function it's declared in (function-scoped), so it can be used anywhere inside that function. 🌍
Hoisting: JavaScript "hoists" or moves var declarations to the top of the function, but only the declaration, not the value.
This can sometimes cause confusion. 😕
Example:
var name = "Alice"; // Variable declared with 'var'
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let– The New Standard 🌱
Scope: let is block-scoped, which means it's only available inside the block (curly braces {}) where it’s declared.
This makes it more predictable. 🧱
Reassignable: You can change the value of a let variable if needed. 📝
Example:
let age = 25; // Variable declared with 'let'
age = 30; // You can reassign it
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const– The Permanent One 🔒
Scope: Like
let,constis also block-scoped. ⛓️Non-Reassignable: Once a value is assigned to a
constvariable, it can't be changed. This is used when you don’t want the value to change. ❌
Example:
const birthYear = 1995; // Variable declared with 'const'
birthYear = 2000; // Error! You can't change it
When to Use Them:
Use let when you need to update the variable’s value later.
Use const when the value should stay the same (like a constant).
Avoid var in modern JavaScript because let and const are more reliable.
By understanding let, const, and var, you'll write cleaner, more predictable JavaScript! 🎯
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