原生代码怎么回调通知h5页面的js方法

页面上调用原生代码，实现一个扫描功能，当后台扫描完成后，如何通知页面呢？目前我的做法是用的定时器，有什么其他的方法吗？后台应该怎么写才能调用js function？

zDoorService = plus.android.importClass("com.zhsq.kmh.DoorService");  
zservice = new zDoorService();  
zmain = plus.android.runtimeMainActivity();  
zservice.scanDevice(zmain);  
zInter = setInterval(function() {  
    if(zservice.getScaning() == false){  
        zserviceId = zservice.getDevs();  
        if(!zserviceId){  
            mui.alert("暂未匹配到设备，请重试");  
        }else{  
            mui.alert("匹配成功，设备id："+zserviceId);  
        }  
        clearInterval(zInter);  
        zInter = null;  
    }  
}, 100);

public class DoorService {  
    private static final String RET = "ret";  
    private static final int SEC = 3;  
    private ArrayList<String> devs;  
    private Boolean scaning = false;  
    public void scanDevice(Context context) {  
        scaning = true;  
        try {  
            ScanCallback callback = new ScanCallback() {  
                @Override  
                public void onScanResult(ArrayList<String> arrayList, ArrayList<Integer> arrayList1) {  
                    devs = arrayList;  
                    scaning = false;  
                }  

                @Override  
                public void onScanResultAtOnce(String s, int i) {  

                }  
            };  
            LibDevModel.scanDevice(context, false, SEC, callback);  
        } catch (Exception e) {  
            Log.e(e.getMessage(), e.getMessage());  
        }  

    }  
    public Boolean getScaning() {  
        return scaning;  
    }  
}