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Kaziu
Kaziu

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Hoisting in javascript. Magic of declare order

#javascript #beginners

What is hoisting ??

a variable can be used before it has been declared because it stores in memory

for example

💎 function 

b();

function b(){
  console.log('foo');
}

// "foo" 
// ✅ thanks to hoisting, function has stored in memory before declaring
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▼ But arrow function isn't like that

arrFn();

const arrFn = () => {
  console.log('arrow!!');
}

// 🔥 Uncaught ReferenceError: Cannot access 'arrFn' before initialization
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💎 variable 

console.log(b)
var b  = 10;

// "undefined"
// ✅ default initialization of the var is undefined.
// ❗ initial value = undefined
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the case of const and let

console.log(NAME) // 🔥 Throws ReferenceError exception as the variable value is uninitialized
const NAME = 'kaziu'
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console.log(count) // 🔥 Throws ReferenceError exception as the variable value is uninitialized
let count = 2
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