Learn React Now
  • Table of Content
  • Design Patterns and Techniques
    • Conditional in JSX
    • Async Nature Of setState()
    • Dependency Injection
    • Context Wrapper
    • Event Handlers
    • Flux Pattern
    • One Way Data Flow
    • Presentational vs Container
    • Third Party Integration
    • Passing Function To setState()
    • Decorators
    • Feature Flags
    • Component Switch
    • Reaching Into A Component
    • List Components
    • Format Text via Component
    • Share Tracking Logic
  • Anti-patterns
    • Introduction
    • Props In Initial State
    • findDOMNode()
    • Mixins
    • setState() in componentWillMount()
    • Mutating State
    • Using Indexes as Key
    • Spreading Props on DOM elements
  • Coding Styles
  • Handling UX Variations
    • Introduction
    • Composing UX Variations
    • Toggle UI Elements
    • HOC for Feature Toggles
    • HOC props proxy
    • Wrapper Components
    • Display Order Variations
  • Performance Tips
    • Introduction
    • shouldComponentUpdate() check
    • Using Pure Components
    • Using reselect
  • Styling
    • Introduction
    • Stateless UI Components
    • Styles Module
    • Style Functions
    • npm Modules
    • Base Component
    • Layout Component
    • Typography Component
    • HOC for Styling
  • Gotchas
    • Introduction
    • Pure render checks
    • Synthetic Events
    • Related Links
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  1. Anti-patterns

setState() in componentWillMount()

PreviousMixinsNextMutating State

Last updated 4 years ago

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Avoid async initialization in componentWillMount()

componentWillMount() is invoked immediately before mounting occurs. It is called before render(), therefore setting state in this method will not trigger a re-render. Avoid introducing any side-effects or subscriptions in this method.

Make async calls for component initialization in componentDidMount instead of componentWillMount

function componentDidMount() {
  axios.get(`api/messages`)
    .then((result) => {
      const messages = result.data
      console.log("COMPONENT WILL Mount messages : ", messages);
      this.setState({
        messages: [...messages.content]
      })
    })
}

Related links:

How to become a pro with React setState() in 10 minutes
State and Lifecycle
Understanding React setState