Convert string Lat/Long to number for Google Maps API

Published 2013-06-15

When sending Lat/Long values to the Google Maps API for something like setCenter(), it wants an number value. But the value we pull from an option menu like the one below is a string.

<select id="searchString" onchange="zoomToAddress(this.value);">
<option value="">--Select All--</option>
<option value="43.138092,-89.747988">Luckenbooth Cafe</option>
<option value="43.017218,-89.831479">Aunt Mary's Hooterville Inn</option>

So we want to convert the above strings to numbers that the Maps API can use. We'll place the following inside a function called zoomToAddress.

First we get the value from the option menu as a string and set it to a variable.

var searchString = document.getElementById('searchString').value;

Then we set a variable to find the position of the comma in the string.

var commaPos = searchString.indexOf(',');

Use parseFloat to conver the string to a number while parsing out the Latitude value.

var coordinatesLat = parseFloat(searchString.substring(0, commaPos));

And we do the same for the Longitude.

var coordinatesLong = parseFloat(searchString.substring(commaPos + 1, searchString.length));

Those variables are combined into a new google maps LatLng pair.

var centerPoint = new google.maps.LatLng(coordinatesLat, coordinatesLong);

Then we can use the setCenter() method from the Maps API.