Skip to content
ML SystemPart 1: Core ConceptsChapter 4
CH.04 ~20 min

Modern JS

ES15, Immutability, and Arrow Functions.

ES15ImmutabilityFunctional
  • Apply ES15 features in React development.
  • Implement immutability patterns for state management.
  • Use higher-order array methods to transform UI data.

01 JavaScript Standards & Immutability Viz

Definition

Immutability

The principle that data structures should not be modified directly. Instead, new copies with the desired changes are created.

FeatureDescription
const vs letPrefer const for all references; use let only when reassignment is strictly necessary.
Arrow FunctionsCompact syntax that inherits 'this' from the lexical scope.
DestructuringExtracting properties from objects or arrays directly into variables.

02 High-Order Transformations

Avoid Direct Mutations

Directly modifying a state object (e.g., clicks.left = 1) will fail to trigger a re-render because React's shallow comparison won't detect the change.

Key Takeaways

  1. 1Use 'const' by default to ensure reference stability.
  2. 2Never mutate state directly; always create a new copy.
  3. 3Higher-order functions are essential for rendering lists and filtering data in React.

CH.04

Chapter Complete

Up next:State Management

Chapter Progress

Reading
Exercise

Interact with the visualization

Quiz

System Efficiency Quiz

Test your understanding of caching, message queues, and communication protocols.

Ready to test your knowledge?

5 questionsRandomized from pool70% to pass