使用 each 內的函數值。 .each 函數的函數 (jQuery)

Question

我的函數的以下部分應該顯示許多 lat/lng 坐標之間的距離。 它工作完美，直到下面的“ console.log(dist) ”部分，但我無法從“dist”到每個html“ i ”獲取這些值。

$(".box").each(function() {
    var latlng = $(this).find('.area').data('latlng').split(',');
    var lat1 = latlng[0];
    var lon1 = latlng[1];
    var lat2 = location_lat.toFixed(8);
    var lon2 = location_lon.toFixed(8);
    
    distance(lat1, lon1, lat2, lon2, "K"); // <-- start calculate function
    
    function distance(lat1, lon1, lat2, lon2, unit) {
        if ((lat1 === lat2) && (lon1 === lon2)) {
            return 0;
        }
        else {
            var radlat1 = Math.PI * lat1/180;
            var radlat2 = Math.PI * lat2/180;
            var theta = lon1-lon2;
            var radtheta = Math.PI * theta/180;
            var dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
            
            if (dist > 1) {
                dist = 1;
            }
            
            dist = Math.acos(dist);
            dist = dist * 180/Math.PI;
            dist = dist * 60 * 1.1515; // M = statute miles (default)
            if (unit === "K") { dist = dist * 1.609344; } // K = kilometers
            if (unit === "N") { dist = dist * 0.8684; } // N = nautical miles

            console.log(dist); // <-- works perfect, I got all the different values
            
            var display = $(this).find('.area');
            $(display).find('i').html(dist.toFixed(0)).append(" <em>km</em>"); // <-- doesn´t work, just empty "i"
        }
    }
    
});

我也試過：

...
distance(lat1, lon1, lat2, lon2, "K"); // <-- start calculate function

var display = $(this).find('.area');
$(display).find('i').html(dist.toFixed(0)).append(" <em>km</em>"); // <-- doesn´t work, because "dist" is not defined

...但是“dist”將不再起作用（錯誤：磁盤未定義）。 我的“ .each ”函數有什么問題？ 如何將“距離函數”中的值返回到.each函數部分？

Answer 1

將distance()函數放在循環之外，讓它返回計算出的值。

function distance(lat1, lon1, lat2, lon2, unit) {
    if (lat1 === lat2 && lon1 === lon2) return 0;

    var radlat1 = Math.PI * lat1/180;
    var radlat2 = Math.PI * lat2/180;
    var theta = lon1-lon2;
    var radtheta = Math.PI * theta/180;
    var dist = Math.sin(radlat1) * Math.sin(radlat2) + Math.cos(radlat1) * Math.cos(radlat2) * Math.cos(radtheta);
    
    if (dist > 1) dist = 1;
    
    dist = Math.acos(dist);
    dist = dist * 180/Math.PI;
    dist = dist * 60 * 1.1515; // M = statute miles (default)
    if (unit === "K") { dist = dist * 1.609344; } // K = kilometers
    if (unit === "N") { dist = dist * 0.8684; } // N = nautical miles
    
    return dist;
}

$(".box").each(function() {
    var latlng = $(this).find('.area').data('latlng').split(',');
    var dist = distance(
        latlng[0],
        latlng[1],
        location_lat.toFixed(8),
        location_lon.toFixed(8),
        "K"
    );

    $(this).find('.area i').text(dist.toFixed(0)).append(" <em>km</em>");
});