3 ms·

Some of the API semantics are changing, e.g. componentWillMount can't be trusted any more (it can fire many times) but they're going to be pretty small.

• davnicwil 9y ago
  Whoah, hang on, really? Do you have a source on this or somewhere I can find out more details? This will completey break a lot of libraries, components, etc that rely on the React lifecycle contracts.. Certainly doesn't feel like a small change! :-/
  • acemarke 9y ago
    Several relevant pointers: - https://github.com/facebook/react/issues/7671 https://github.com/facebook/react/issues/7671 - https://twitter.com/dan_abramov/status/790590733468241920 https://twitter.com/dan_abramov/status/790590733468241920 - https://www.reddit.com/r/reactjs/comments/5fg7iq/why_should_ajax_requests_go_in_componentdidmount/ https://www.reddit.com/r/reactjs/comments/5fg7iq/why_should_... - https://daveceddia.com/where-fetch-data-componentwillmount-vs-componentdidmount/ https://daveceddia.com/where-fetch-data-componentwillmount-v... Also see Lin Clark's "React Fiber" talk, linked upthread. Basically, pieces of work can start and be interrupted, and then be restarted, which will mean that `componentWillMount` can be called several times before the component _actually_ mounts.
    • danabramov 9y ago
      To be clear this is irrelevant to React 16 which works in sync mode for compatibility. We'll share more about any changes when we start enabling the async mode in Facebook products and figure out the best migration strategy.
  • lobster_johnson 9y ago
    Fortunately, componentWillMount is largely made redundant by the use of constructors.
    • madeofpalk 9y ago
      Except it's not for when you actually want to know when the component was put into the DOM, or you're running react server-side
      • wayfarer2s 9y ago
        > when you actually want to know when the component was put into the DOM You can use componentDidMount for that and its semantics are still the same.
        • danabramov 9y ago
          Yes, componentDidMount is the place to work with DOM. componentWillMount never worked this way—it is basically a glorified constructor from pre-ES6 era.
        • madeofpalk 9y ago
          Oh apologies - I really the comment as componentDidMount. My bad.