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I have a situation that I am using AJAX to call a page that returns a list of business locations to populate a Google map. My original goal was to display markers for locations whose radius touched the website visitor's location.

Now I only need to know IF the website visitor is within the radius of any one of the locations returned by the ajax call. In the code below, you see a conditional statement "fink <= rs.Records[recno].radius". What I am attempting to do is the first time that statement executes to true, set a cookie and/or call a function and exit the for loop.

As a side question, a friend told me of something called grep (I think). Do I need to loop through an entire list to find if that condition is true? Meaning I know in mySQL I can just query something like "select * from locations where radius < 50". So if my ajax returns 10,000 locations, all I need to know is my website visitor distance within the radius of any any of my locations?

Thanks in advance for any help.

function distance(lat1, lon1, lat2, lon2) 
 var p = 0.017453292519943295; // Math.PI / 180
 var c = Math.cos;
 var a = 0.5 - c((lat2 - lat1) * p) / 2 +
 c(lat1 * p) * c(lat2 * p) *
 (1 - c((lon2 - lon1) * p)) / 2;
 return .62137119 * (12742 * Math.asin(Math.sqrt(a))); // 2 * R; R = 6371 km



function getMarkers(lat, lng, city, state) 
 $.ajax(
 url: '/getMarkers.asp?state=Nebraska',
 type: 'GET',
 dataType: 'text',
 error: function(xhr, status, errorstr) 
 console.log(errorstr); // just show error message in console if there was an error
 ,
 ).done(function(response_obj) 
 console.log(response_obj);
 var rs = eval(response_obj);
 if (rs) // has a non-null value
 var str = rs.RecordCount + " Users:<br/>";

 for (var recno = 0; recno < rs.RecordCount; recno++) 
 fink = distance(<%= session("uLat") %>, <%= session("uLng") %>, rs.Records[recno].latitude, rs.Records[recno].longitude);
 if (fink <= rs.Records[recno].radius) 
 $(".markers").append("<li data-center='" + rs.Records[recno].latitude + ", " + rs.Records[recno].longitude + "' data-locale='" + recno + "' data-radius='" + rs.Records[recno].radius + "' data-location='" + rs.Records[recno].city + "'>" + rs.Records[recno].street + "</li>n");
 
 
 initMap();
 else 
 str = "No users found"
 
 );

Use break;

 for (var recno = 0; recno < rs.RecordCount; recno++) 
 fink = distance(<%= session("uLat") %>, <%= session("uLng") %>, rs.Records[recno].latitude, rs.Records[recno].longitude);
 if (fink <= rs.Records[recno].radius) 
 $(".markers").append("<li data-center='" + rs.Records[recno].latitude + ", " + rs.Records[recno].longitude + "' data-locale='" + recno + "' data-radius='" + rs.Records[recno].radius + "' data-location='" + rs.Records[recno].city + "'>" + rs.Records[recno].street + "</li>n");
 break;
 
 

And if you want to know if any were found, you can set a variable.

 found_close = false;
 for (var recno = 0; recno < rs.RecordCount; recno++) 
 fink = distance(<%= session("uLat") %>, <%= session("uLng") %>, rs.Records[recno].latitude, rs.Records[recno].longitude);
 if (fink <= rs.Records[recno].radius) 
 $(".markers").append("<li data-center='" + rs.Records[recno].latitude + ", " + rs.Records[recno].longitude + "' data-locale='" + recno + "' data-radius='" + rs.Records[recno].radius + "' data-location='" + rs.Records[recno].city + "'>" + rs.Records[recno].street + "</li>n");
 found_close = true;
 break;
 
 
 if (!found_close) 
 // do something