Do you understand variables : Let, Const and Ver in JavaScript? IF NO then let go ๐Ÿ˜‰

Erasmus Kotoka - Sep 16 - - Dev Community

In JavaScript, variables are like containers that store data. There are three ways to create (or declare) these containers: var, let, and const.

Letโ€™s look at what makes them different! ๐ŸŒŸ

  1. var โ€“ The Old-School Way ๐Ÿ“œ

Scope: var works within the function it's declared in (function-scoped), so it can be used anywhere inside that function. ๐ŸŒ

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. ๐Ÿ˜•

Example:


var name = "Alice"; // Variable declared with 'var'

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  1. let โ€“ The New Standard ๐ŸŒฑ

Scope: let is block-scoped, which means it's only available inside the block (curly braces {}) where itโ€™s declared.

This makes it more predictable. ๐Ÿงฑ

Reassignable: You can change the value of a let variable if needed. ๐Ÿ“

Example:


let age = 25; // Variable declared with 'let'

age = 30;   // You can reassign it

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  1. const โ€“ The Permanent One ๐Ÿ”’
  • Scope: Like let, const is also block-scoped. โ›“๏ธ

  • Non-Reassignable: Once a value is assigned to a const variable, it can't be changed. This is used when you donโ€™t want the value to change. โŒ

Example:


const birthYear = 1995; // Variable declared with 'const'

birthYear = 2000; // Error! You can't change it

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When to Use Them:

Use let when you need to update the variableโ€™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! ๐ŸŽฏ

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