Edit

Example of making a WFS GetFeature request with a filter.

This example generates a GetFeature request which uses a PropertyIsEqualTo and a PropertyIsLike filter, and then posts the request to load the features that match the query.

main.js
import 'ol/ol.css';
import Map from 'ol/Map';
import VectorSource from 'ol/source/Vector';
import View from 'ol/View';
import XYZ from 'ol/source/XYZ';
import {GeoJSON, WFS} from 'ol/format';
import {Stroke, Style} from 'ol/style';
import {Tile as TileLayer, Vector as VectorLayer} from 'ol/layer';
import {
  and as andFilter,
  equalTo as equalToFilter,
  like as likeFilter,
} from 'ol/format/filter';

var vectorSource = new VectorSource();
var vector = new VectorLayer({
  source: vectorSource,
  style: new Style({
    stroke: new Stroke({
      color: 'rgba(0, 0, 255, 1.0)',
      width: 2,
    }),
  }),
});

var key = 'Get your own API key at https://www.maptiler.com/cloud/';
var attributions =
  '<a href="https://www.maptiler.com/copyright/" target="_blank">&copy; MapTiler</a> ' +
  '<a href="https://www.openstreetmap.org/copyright" target="_blank">&copy; OpenStreetMap contributors</a>';

var raster = new TileLayer({
  source: new XYZ({
    attributions: attributions,
    url: 'https://api.maptiler.com/tiles/satellite/{z}/{x}/{y}.jpg?key=' + key,
    maxZoom: 20,
  }),
});

var map = new Map({
  layers: [raster, vector],
  target: document.getElementById('map'),
  view: new View({
    center: [-8908887.277395891, 5381918.072437216],
    maxZoom: 19,
    zoom: 12,
  }),
});

// generate a GetFeature request
var featureRequest = new WFS().writeGetFeature({
  srsName: 'EPSG:3857',
  featureNS: 'http://openstreemap.org',
  featurePrefix: 'osm',
  featureTypes: ['water_areas'],
  outputFormat: 'application/json',
  filter: andFilter(
    likeFilter('name', 'Mississippi*'),
    equalToFilter('waterway', 'riverbank')
  ),
});

// then post the request and add the received features to a layer
fetch('https://ahocevar.com/geoserver/wfs', {
  method: 'POST',
  body: new XMLSerializer().serializeToString(featureRequest),
})
  .then(function (response) {
    return response.json();
  })
  .then(function (json) {
    var features = new GeoJSON().readFeatures(json);
    vectorSource.addFeatures(features);
    map.getView().fit(vectorSource.getExtent());
  });
index.html
<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8">
    <title>WFS - GetFeature</title>
    <!-- Pointer events polyfill for old browsers, see https://caniuse.com/#feat=pointer -->
    <script src="https://unpkg.com/elm-pep"></script>
    <style>
      .map {
        width: 100%;
        height:400px;
      }
    </style>
  </head>
  <body>
    <div id="map" class="map"></div>
    <script src="main.js"></script>
  </body>
</html>
package.json
{
  "name": "vector-wfs-getfeature",
  "dependencies": {
    "ol": "6.5.0"
  },
  "devDependencies": {
    "parcel": "^2.0.0-beta.1"
  },
  "scripts": {
    "start": "parcel index.html",
    "build": "parcel build --public-url . index.html"
  }
}