前端js中Map取值问题，如下：

Question

我在前端js中写
var Map = JSON.stringify(layer.p1);
console.log(Map);
页面得到：
{"type":"line","x1":429,"y1":135,"x2":374,"y2":182,"x3":432,"y3":220,"x4":559,"y4":306,"x5":605,"y5":191,"x6":458,"y6":100}
我该如何从数组中获得x，y的最大值与最小值？

Answer 1

var map = {"type":"line","x1":429,"y1":135,"x2":374,"y2":182,"x3":432,"y3":220,"x4":559,"y4":306,"x5":605,"y5":191,"x6":458,"y6":100};
var xmax = -Infinity;
var ymax = -Infinity;
var xmin = Infinity;
var ymin = Infinity;
for (var n in map) {
    if (n.charAt(0)=="x") {
        xmax = Math.max(map[n],xmax);
        xmin = Math.min(map[n],xmin);
    }
    if (n.charAt(0)=="y") {
        ymax = Math.max(map[n],ymax);
        ymin = Math.min(map[n],ymin);
    }
}
alert("xmax = "+xmax+", ymax = "+ymax+", xmin = "+xmin+", ymin = "+ymin);