``````<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
<script src="https://cdn.bootcss.com/jquery/3.3.1/jquery.min.js"></script>
<script src="https://cdn.bootcss.com/lodash.js/4.17.10/lodash.js"></script>

<body>
<div id="main"></div>
</body>
</html>
``````
``````
var bounds = null;
var isPointInPolygon = function(point, pts){

//下述代码来源：http://paulbourke.net/geometry/insidepoly/，进行了部分修改
//基本思想是利用射线法，计算射线与多边形各边的交点，如果是偶数，则点在多边形外，否则
//在多边形内。还会考虑一些特殊情况，如点在多边形顶点上，点在多边形边上等特殊情况。

var N = pts.length;
var boundOrVertex = true; //如果点位于多边形的顶点或边上，也算做点在多边形内，直接返回true
var intersectCount = 0;//cross points count of x
var precision = 2e-10; //浮点类型计算时候与0比较时候的容差
var p1, p2;//neighbour bound vertices
var p = point; //测试点

p1 = pts[0];//left vertex
for(var i = 1; i <= N; ++i){//check all rays
if(p.equals(p1)){
return boundOrVertex;//p is an vertex
}

p2 = pts[i % N];//right vertex
if(p.lat < Math.min(p1.lat, p2.lat) || p.lat > Math.max(p1.lat, p2.lat)){//ray is outside of our interests
p1 = p2;
continue;//next ray left point
}

if(p.lat > Math.min(p1.lat, p2.lat) && p.lat < Math.max(p1.lat, p2.lat)){//ray is crossing over by the algorithm (common part of)
if(p.lng <= Math.max(p1.lng, p2.lng)){//x is before of ray
if(p1.lat == p2.lat && p.lng >= Math.min(p1.lng, p2.lng)){//overlies on a horizontal ray
return boundOrVertex;
}

if(p1.lng == p2.lng){//ray is vertical
if(p1.lng == p.lng){//overlies on a vertical ray
return boundOrVertex;
}else{//before ray
++intersectCount;
}
}else{//cross point on the left side
var xinters = (p.lat - p1.lat) * (p2.lng - p1.lng) / (p2.lat - p1.lat) + p1.lng;//cross point of lng
if(Math.abs(p.lng - xinters) < precision){//overlies on a ray
return boundOrVertex;
}

if(p.lng < xinters){//before ray
++intersectCount;
}
}
}
}else{//special case when ray is crossing through the vertex
if(p.lat == p2.lat && p.lng <= p2.lng){//p crossing over p2
var p3 = pts[(i+1) % N]; //next vertex
if(p.lat >= Math.min(p1.lat, p3.lat) && p.lat <= Math.max(p1.lat, p3.lat)){//p.lat lies between p1.lat & p3.lat
++intersectCount;
}else{
intersectCount += 2;
}
}
}
p1 = p2;//next ray left point
}

if(intersectCount % 2 == 0){//偶数在多边形外
return false;
} else { //奇数在多边形内
return true;
}
};

\$('#main').append('<div>Do while get the data</div>');

\$.get('https://lc-OnsG2j7w.cn-n1.lcfile.com/9777e2380374792ea6d6.json',function(res){
bounds = res.bounds;

\$('#main').append('<div>Start testing!</div>');
\$('#main').append('<div>------</div>');

doTest(200);
doTest(600);
doTest(1000);
doTest(10000);

\$('#main').append('<div>------</div>');

\$('#main').append('<div>Done!</div>');
});

getTestData = function(dataLength){
var points = [];
for(var i=0;i<dataLength;i++){
points.push({
lat:_.random( 20.000001,52.99999),
lng:_.random(99.000000,150.999939),
equals:function(){
return false;
}
});
};

return points;
}

doTest = function(dataLength){
var points = getTestData(200);
for(var i=0;i<600;i++){
points.push({
lat:_.random( 20.000001,52.99999),
lng:_.random(99.000000,150.999939),
equals:function(){
return false;
}
});
};

var startTime = new Date();
for(var i=0;i<points.length;i++){
var p = points[i];
console.log(p.lat +','+p.lng+' is in china: '+isPointInPolygon(p,bounds));
}
\$('#main').append('<div>'+dataLength+ ' many datas, Total times: '+ (new Date().getTime() - startTime.getTime())+' ms '+'</div>');
};

});``````

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