反应和传单

Question

I'm trying to use Leaflet in my React App. I'm running into an issue. Leaflet.js requires the div component to pre-exist when initiating the map. React doesn't "create" the div until it renders the component, so leaflet is throwing an error. Both getDOMNode() and findDOMNode() return "not a function" for whatever reason.

Code:

import React from 'react';
import {render} from 'react-dom';
import L from 'leaflet';

...a little later

export default class Mapbox extends React.Component {
  render() {
    var map = L.map('map').setView([51.505, -0.09], 13);

L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {
    attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
}).addTo(map);

    return (

      <div id="map">
    <h1>hi</h1>
    </div>
    );

This returns an error that "Map Container not Found".

Thanks.

Answer 1

You can initialize map inside componentDidMount

class Mapbox extends React.Component {
  componentDidMount() {
    this.map();
  }

  map() {
    var map = L.map('map').setView([51.505, -0.09], 13);

    L.tileLayer('http://{s}.tile.osm.org/{z}/{x}/{y}.png', {
      attribution: '&copy; <a href="http://osm.org/copyright">OpenStreetMap</a> contributors'
    }).addTo(map);
  }

  render() {
    return <div id="map">xx</div>  
  }
}

Example

Answer 2

The other answers are great if you're using class components. If you have to use it with functional components (using Hooks ) than you might need to code useRef .

function Map({}) {
  // define the ref here
  const mapRef = useRef(null);

  useEffect( () => {
// set the initialized map to the ref
    mapRef.current = L.map('map').setView([51.505, 3], 13);
    
    }, []);

// pass it in the required div node
  return (
    <div ref={mapRef} id="map" className="p-2">
    </div>
  );

}

In this way the map will be initialized after the DOM node is rendered.

Reference: React hooks .

Answer 3

Since react 16.3 there is a new method for creating references easily.

note:the references can be stored in constructor as the refernces can be created prior to the jsx div is created.

class Map extends React.Component {


  componentDidMount() {
   this.map = React.createRef();
   var map = L.map(this.map).setView([51.505, -0.09], 13);
  }

  render() {
    return <div ref={this.map}></div>
  }
}

Answer 4

Use "refs". Refs is used to return a reference to the element. docs here

class Map extends React.Component {

  componentDidMount() {
    const node = this.node;
    var map = var map = L.map(node).setView([51.505, -0.09], 13);
  }

  render() {
    return <div ref={(node) => { this.node = node }}></div>
  }
}