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  • JS Principles
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      • typeof operator
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      • Conditional (ternary) operator
        • Coercion vs Conversion
      • Event-driven programming
      • Factory Function
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      • Strict mode
      • super() keyword
      • What are memory leaks?
      • Micro-tasks within an event loop (Summary)
      • Macro-tasks within an event loop (Summary)
      • null vs undefined
    • Memory Management
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      • Impure vs Pure Functions
      • Factory functions
  • JavaScript Objects & Arrays
    • Introducing JavaScript objects
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        • Map
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        • Array.of()
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        • Inheritance with the prototype chain
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  • JavaScript Mid
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      • var, let, and const
      • Fetch API (function)
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      • Synchronous vs Asynchronous
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      • 'This' keyword
      • Functional Programming
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    • The TypeScript Handbook
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    • Mathematical
      • JavaScript | Math.E() function
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      • Math.imul( ) Function
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      • Math pow( ) Method
      • Math.sign( ) Function
      • Math sqrt( ) Method
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  1. JavaScript Mid
  2. JavaScript & ES

Destructuring assignment

The destructuring assignment syntax is a JavaScript expression that makes it possible to unpack values from arrays, or properties from objects, into distinct variables.

let a, b, rest;
[a, b] = [10, 20];

console.log(a);
// expected output: 10

console.log(b);
// expected output: 20

[a, b, ...rest] = [10, 20, 30, 40, 50];

console.log(rest);
// expected output: Array [30,40,50]
let a, b, rest;
[a, b] = [10, 20];
console.log(a); // 10
console.log(b); // 20

[a, b, ...rest] = [10, 20, 30, 40, 50];
console.log(a); // 10
console.log(b); // 20
console.log(rest); // [30, 40, 50]

({ a, b } = { a: 10, b: 20 });
console.log(a); // 10
console.log(b); // 20


// Stage 4(finished) proposal
({a, b, ...rest} = {a: 10, b: 20, c: 30, d: 40});
console.log(a); // 10
console.log(b); // 20
console.log(rest); // {c: 30, d: 40}
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Last updated 4 years ago

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