小编典典

在Javascript中使用Haversine公式

javascript

我正在尝试使用Haversine距离公式但是我无法使用它,请参见以下代码

    function test() { 
    var lat2 = 42.741; 
    var lon2 = -71.3161; 
    var lat1 = 42.806911; 
    var lon1 = -71.290611;

    var R = 6371; // km 
    //has a problem with the .toRad() method below.
    var dLat = (lat2-lat1).toRad();  
    var dLon = (lon2-lon1).toRad();  
    var a = Math.sin(dLat/2) * Math.sin(dLat/2) + 
                    Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) * 
                    Math.sin(dLon/2) * Math.sin(dLon/2);  
    var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
    var d = R * c;

    alert(d); 
}

错误是:

Uncaught TypeError: Object -0.06591099999999983 has no method 'toRad'

我知道这是因为它需要执行以下操作:

Number.prototype.toRad = function() {
return this * Math.PI / 180;
}

但是,当我将此放在函数下方时,它仍然返回相同的错误消息。如何使用助手方法?还是有其他方法可以对此进行编码?谢谢!


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2020-05-01

共1个答案

小编典典

此代码有效:

Number.prototype.toRad = function() {
   return this * Math.PI / 180;
}

var lat2 = 42.741; 
var lon2 = -71.3161; 
var lat1 = 42.806911; 
var lon1 = -71.290611;

var R = 6371; // km 
//has a problem with the .toRad() method below.
var x1 = lat2-lat1;
var dLat = x1.toRad();  
var x2 = lon2-lon1;
var dLon = x2.toRad();  
var a = Math.sin(dLat/2) * Math.sin(dLat/2) + 
                Math.cos(lat1.toRad()) * Math.cos(lat2.toRad()) * 
                Math.sin(dLon/2) * Math.sin(dLon/2);  
var c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1-a)); 
var d = R * c;

alert(d);
2020-05-01