javascript check if file exists [duplicate]

Answer 1

You can include a function like this:

function fileExists(url)
{
    var http = new XMLHttpRequest();
    http.open('HEAD', url, false);
    http.send();
    return http.status!=404;
}

And then modify your code like so:

var adm1_path = "../topo/"+d.id+"_adm1.json"
if (!fileExists(adm1_path)) {
    alert('We couldn't find that country!') //or some other suitable error/display mechanism
    return;
}

d3.json(adm1_path, function(error, topology) {