function testImage(URL) {
    var tester=new Image();
    tester.onLoad=isGood;
    tester.onError=isBad;
    tester.src=URL;
}

function isGood() {
    alert('That image exists!');
}

function isBad() {
    alert('That image does no exist!');
}
testImage("Provino11.png");