openlayers.js通过map遍历所有图层中的feature

具体API参考openlayer

代码：

var map = new ol.Map({
    layers: [gaodeMapLayer],
    view: new ol.View({
        center: [0.281830008803421,0.245858887676368],
        projection: 'EPSG:4326',
        zoom: 14
    }),
    target: 'map'
});

var vectorLayer = new ol.layer.Vector({
    source: new ol.source.Vector({
      url: 'data/6fnew.geojson',
    //   url: 'data/28new.geojson',
      format: new ol.format.GeoJSON(),
    }),
    // source: source,
    style: styles
});

map.addLayer(vectorLayer)

let layers = map.getLayers().a;

for(let i = 1; i < 10; i++) {
    clearInterval(i);
}

var i =1;
var timer = setInterval(function(){
    if(i == layers.length) {
        clearInterval(timer)
    }else{
        let s = layers[i].getSource().l
        console.log('source.l',s)
    }
    i++;
},1000)