选择多个要素【译】

原文链接及内容

原文链接：https://openlayers.org/en/latest/examples/select-multiple-features.html

在这个例子中，为地图对象注册了一个的singleclick监听器，用于从数组中添加和删除要素。

main.js代码如下：

import Fill from 'ol/style/Fill.js';
import GeoJSON from 'ol/format/GeoJSON.js';
import Map from 'ol/Map.js';
import Stroke from 'ol/style/Stroke.js';
import Style from 'ol/style/Style.js';
import VectorLayer from 'ol/layer/Vector.js';
import VectorSource from 'ol/source/Vector.js';
import View from 'ol/View.js';
import {fromLonLat} from 'ol/proj.js';

const highlightStyle = new Style({
  fill: new Fill({
    color: '#EEE',
  }),
  stroke: new Stroke({
    color: '#3399CC',
    width: 2,
  }),
});

const vector = new VectorLayer({
  background: 'white',
  source: new VectorSource({
    url: 'https://openlayers.org/data/vector/us-states.json',
    format: new GeoJSON(),
  }),
});

const map = new Map({
  layers: [vector],
  target: 'map',
  view: new View({
    center: fromLonLat([-100, 38.5]),
    zoom: 4,
    multiWorld: true,
  }),
});

const selected = [];

const status = document.getElementById('status');

map.on('singleclick', function (e) {
  map.forEachFeatureAtPixel(e.pixel, function (f) {
    const selIndex = selected.indexOf(f);
    if (selIndex < 0) {
      selected.push(f);
      f.setStyle(highlightStyle);
    } else {
      selected.splice(selIndex, 1);
      f.setStyle(undefined);
    }
  });

  status.innerHTML = '&nbsp;' + selected.length + ' selected features';
});