今天做项目有个需求是在地图上圈一个多边形区域，判断某个点是否在所圈多边形区域内。

js代码：

isContainsPoint: function (point) {

        var count = this.featurePoints.length,

            flag = false;

        for (var i = 0, j = count - 1; i < count; j = i++) {

            if (((point.lat >= this.featurePoints[i].lat && point.lat < this.featurePoints[j].lat) ||

                (point.lat < this.featurePoints[i].lat && point.lat >= this.featurePoints[j].lat)) &&

                (point.lng < ((this.featurePoints[j].lng - this.featurePoints[i].lng) * (point.lat - this.featurePoints[i].lat) /

                    (this.featurePoints[j].lat - this.featurePoints[i].lat) + this.featurePoints[i].lng))) {

                flag = !flag;

            }

        }

        return flag;

    } 

注意：point 是判断是否在多边形内的点

featurePoints是多边形的顶点坐标，不重复，有顺序（顺逆时针都可以）