Clear TileWMS source layer openlayers 5

Question

I'm trying to change raster layer with a selector.

I don't understand why the clear method don't work on tileWMS however it's on the API doc...

For a vector source, on an other app, it work :

var cqlFilter = 'date_debut BETWEEN 1000 AND 2000 OR date_fin BETWEEN 1000 AND 2000';
var urlTemplate = 'http://serveradress/geoserver/applications/wfs?service=WFS&' +
'version=1.0.0&request=GetFeature&' +
'typeNames=applications:patrimoine&' +
'CQL_FILTER=' + cqlFilter +
'&outputFormat=application/json&' +
'srsName=EPSG:4326';
console.log(urlTemplate);
var _vectorSource = new ol.source.Vector({
  format: new ol.format.GeoJSON(),
  url: function() {return urlTemplate;}
});

function changeDate(years) {
  var dateMin = years[0];
  var dateMax = years[1];
  var cqlNewFilter = '(date_debut BETWEEN '+ dateMin + ' AND ' + dateMax + ' OR date_fin BETWEEN ' + dateMin + ' AND ' + dateMax + ')';
  urlTemplate = 'http://serveradress/geoserver/applications/wfs?service=WFS&' +
  'version=1.0.0&request=GetFeature&' +
  'typeNames=applications:patrimoine&' +
  'CQL_FILTER=' + cqlNewFilter +
  '&outputFormat=application/json&' +
  'srsName=EPSG:4326';
  _vectorSource.clear(true);
  _vectorSource.refresh();
};

var _cluster = new ol.source.Cluster({
    distance: 50,
    source: _vectorSource
});

var _layer = new ol.layer.Vector({
  source: _cluster,
  style: _patrimoineStyle
});

But whith a TileWMS layer it don't work, it tells me that _rasterSource.clear is not a function :

var anneeCouche = "2016_20cm";

var _rasterSource = new ol.source.TileWMS({
  url: 'http://serveradress/geoserver/raster/wms?',
  params: {LAYERS: 'raster:ortho'+anneeCouche}
});

function changeDate(annee) {
  if (annee === '2013') {
    var anneeCouche = "2013_20cm";
  } else {
    var anneeCouche = "2016_20cm";
  };
  _rasterSource.clear(true);
  _rasterSource.refresh();
};

var _layer = new ol.layer.Tile({
  title: 'Ortho',
  source: _rasterSource
});

Answer 1

Changing the value of anneeCouche won't update the value of params which have already been evaluated. Instead you should use updateParams (the source should be automatically refreshed)

function changeDate(annee) {
  if (annee === '2013') {
    var anneeCouche = "2013_20cm";
  } else {
    var anneeCouche = "2016_20cm";
  };
  _rasterSource.updateParams({LAYERS: 'raster:ortho'+anneeCouche});
};