Check if file exist using script.

1)
same domain this should work:
function UrlExists(url)
{
    var http = new XMLHttpRequest();
    http.open('HEAD', url, false);
    http.send();
    return http.status!=404;
}


or

function fileExists(url) {
    if(url){
        var req = new XMLHttpRequest();
        req.open('GET', url, false);
        req.send();
        return req.status==200;
    } else {
        return false;
    }
}

2)
function ImageExist(url)
{
   var img = new Image();
   img.src = url;
   return img.height != 0;
}

3)

<img src="image.gif" onerror="imgError()" />

4)

$.get(url)
    .done(function() { 
        // exists code 
    }).fail(function() { 
        // not exists code
    })

5)

$.ajax({
    url:'http://www.example.com/somefile.ext',
    type:'HEAD',
    error: function()
    {
        //file not exists
    },
    success: function()
    {
        //file exists
    }
});

For a client computer this can be achieved by:

try
{
  var myObject, f;
  myObject = new ActiveXObject("Scripting.FileSystemObject");
  f =   myObject.GetFile("C:\\img.txt");
  f.Move("E:\\jarvis\\Images\\");
}
catch(err)
{
  alert("file does not exist")
}

6)Image exists. 

function checkImage(src) {
  var img = new Image();
  img.onload = function() {
      // code to set the src on success
      $('#image-test').css('background', 'url(' + src + ') no-repeat 50% 50%');
  };
  img.onerror = function() {
    // doesn't exist or error loading
    alert('no image');
  };

  img.src = src; // fires off loading of image
}

checkImage('http://www.google.com/images/logo_sm.gif');