javascript - Hold off React Render until after request - Stack Overflow

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I have a ponent that's being loaded with the initial state:

  getInitialState: function() {
    return {
      panel: "deals",
      showExtension: false,
      person: {}

    };
  },

And I have this to find a person:

  ponentDidMount: function() {
    this.findPersonFromBackground();
  },
  findPersonFromBackground: function() {
    chrome.runtime.sendMessage({ action: "findPerson", email: this.props.currentEmail.from_email }, function(person) {
      this.setState({person: person});
    }.bind(this));
  },

So all works fine. If the person is found, I render one thing, and if not, something else.

When the first is found, the view goes from non-found state to found state real fast, since the API calls are pretty quick.

What's the best way to wait to render until that first call es back?

I have a ponent that's being loaded with the initial state:

  getInitialState: function() {
    return {
      panel: "deals",
      showExtension: false,
      person: {}

    };
  },

And I have this to find a person:

  ponentDidMount: function() {
    this.findPersonFromBackground();
  },
  findPersonFromBackground: function() {
    chrome.runtime.sendMessage({ action: "findPerson", email: this.props.currentEmail.from_email }, function(person) {
      this.setState({person: person});
    }.bind(this));
  },

So all works fine. If the person is found, I render one thing, and if not, something else.

When the first is found, the view goes from non-found state to found state real fast, since the API calls are pretty quick.

What's the best way to wait to render until that first call es back?

• javascript
• reactjs

Share Improve this question Follow asked Sep 25, 2014 at 21:20 brandonhilkertbrandonhilkert 4,48577 gold badges2626 silver badges3939 bronze badges

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4 Answers 4

Sorted by: Reset to default 5

There's no good way to do what you're asking, which is to keep a ponent from rendering at all until some asynchronous operation that the ponent initiates pletes; the best you can do is use techniques from other answers to this question to render something slightly different in the case that it's not plete.

However, the problem you're actually trying to solve is preventing the brief flash of alternatively-rendered content if the API request starts and the pletes very quickly. If you move the asynchronous operation to the parent of your ponent, you can ensure that the async operation pletes before you ever even render your child.

If the Chrome runtime requests are consistently fast, this may be fine, but in the general case, it's worth considering what the behavior will be if the async operation takes a longer time to plete.

One way you can handle it is with the enum pattern. In this code, this.state.person is either the loading sentinel, the notFound sentinel, or the actual person.

var status = {loading: {}, notFound: {}};

// ...

getInitialState: function(){
  return {person: status.loading}
},
fetchPerson: function(){
  doFetchPerson(function(person){
    if (person) this.setState({person: person})
    else this.setState({person: status.notFound})
  }.bind(this))
},
render: function(){
  var person = this.state.person)
  if (person === status.loading) ...
  else if (person === status.notFound) ...
  else ...
}

Is this more of a design question? You could show a spinner, an empty box, a shapes only preview (like Facebook feed), or nothing at all.

If this is a technical question then return null in render().

maybe you need this project: https://github./toplan/react-hold

You can use the placeholder to keep the shape of your ponent.

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