AMap.MarkerClusterer is not a constructor

willie

根据示例，创建点聚合时报错： Uncaught TypeError: AMap.MarkerClusterer is not a constructor

代码如下
for(...){
markers.push(
        new AMap.Marker({
                map: map,
                position: [lnghts[i].surveyLongitude, lnghts[i].surveyLatitude],
                icon: icon,
                offset: new AMap.Pixel(-12, -36)
                })
       );

}
var count = markers.length;
        var _renderCluserMarker = function(context) {
        var factor = Math.pow(context.count / count, 1 / 18)
        var div = document.createElement('div');
        var Hue = 180 - factor * 180;
        var bgColor = 'hsla(' + Hue + ',100%,50%,0.7)';
        var fontColor = 'hsla(' + Hue + ',100%,20%,1)';
        var borderColor = 'hsla(' + Hue + ',100%,40%,1)';
        var shadowColor = 'hsla(' + Hue + ',100%,50%,1)';
        div.style.backgroundColor = bgColor
        var size = Math.round(30 + Math.pow(context.count / count, 1 / 5) * 20);
        div.style.width = div.style.height = size + 'px';
        div.style.border = 'solid 1px ' + borderColor;
        div.style.borderRadius = size / 2 + 'px';
        div.style.boxShadow = '0 0 1px ' + shadowColor;
        div.innerHTML = context.count;
        div.style.lineHeight = size + 'px';
        div.style.color = fontColor;
        div.style.fontSize = '14px';
        div.style.textAlign = 'center';
        context.marker.setOffset(new AMap.Pixel(-size / 2, -size / 2));
        context.marker.setContent(div)
}

var cluster = new AMap.MarkerClusterer(map, markers, {
        gridSize: 80,
        renderCluserMarker: _renderCluserMarker
});