(function (window) {        "use strict";        /**         * 判断给出的坐标点是否在多边形内         * */        function pointInPolygon(targetPoint, targetPoints) {            var leftPointCount = 0;            var rightPointCount = 0;//左右点的个数            var _points = [];            //第一步：取出所有的点，并计算交点坐标            for (var i = 0, _length = targetPoints.length - 1; i < _length; i++) {                var p1 = targetPoints[i], p2 = targetPoints[i + 1];//取出当前点和当前点的下一个点                var point = _calcCrossoverPoint(targetPoint, p1, p2);                //如果交点有效，则保存                if (point) {                    _points.push(point);                }            }//            第二步：计算给定的坐标点，左右两边的交点个数，奇数在范围内，偶数则不在            for (var j = 0, length = _points.length; j < length; j++) {                var x = _points[j];                if (x === targetPoint.x) {                    return false;//在线上，直接返回不在范围内                } else {                    (targetPoint.x !== x && targetPoint.x > x) ? leftPointCount++ : rightPointCount++;                }            }            //判断交点个数            return (leftPointCount % 2 !== 0 && rightPointCount % 2 !== 0);        }        /**         * 算交点坐标，坐标点在扫描行上或者上方时，交点无效         * @param targetPoint         * @param startPoint         * @param endPoint         * @returns {*}         */        function _calcCrossoverPoint(targetPoint, startPoint, endPoint) {            var crossoverPointX = startPoint.x - ((startPoint.y - targetPoint.y) * (startPoint.x - endPoint.x) / (startPoint.y - endPoint.y));//            判断交点坐标是否有效，即交点在startPoint，endPoint构成的线段范围内            if ((startPoint.y < targetPoint.y && endPoint.y >= targetPoint.y) || (endPoint.y < targetPoint.y && startPoint.y >= targetPoint.y)) {                if ((crossoverPointX >= startPoint.x && crossoverPointX <= endPoint.x) || (crossoverPointX <= startPoint.x && crossoverPointX >= endPoint.x)) {                    return crossoverPointX;                } else {                    return false;                }            } else {                return false;            }        }        var isIn = pointInPolygon({x: 4, y: 4}, [{x: 2, y: 1}, {x: 1, y: 3}, {x: 3, y: 5}, {x: 5, y: 4}, {            x: 4,            y: 1        }, {x: 3, y: 2}, {            x: 2,            y: 1        }]);        console.log(isIn);    })(window);