JS 移动动画

function moveElement(elementId, final_x, final_y,interval) {
if (!document.getElementById) return false;
if (!document.getElementById(elementId)) return false;
var elem = document.getElementById(elementId);
var elementLeft = parseInt(elem.style.left);
var elementTop = parseInt(elem.style.top);
if (elementLeft == final_x && elementTop == final_y) {
return true;
}
if (elementLeft < final_x) {
elementLeft++;
}
if (elementLeft > final_x) {
elementLeft--;
}
if (elementTop < final_y) {
elementTop++ ;
}
if (elementTop > final_y) {
elementTop--;
}
elem.style.left = elementLeft + 'px';
elem.style.top = elementTop + 'px';
var repeat = "moveElement('"+ elementId + "'," + final_x + "," + final_y + "," + interval + ")";
movement = setTimeout(repeat, interval);
}

　　 function positionMsg() {
var elem = document.getElementById('message');
elem.style.position = 'absolute';
elem.style.left = '10px';
elem.style.top = '100px';
moveElement('message',200,500,100);
};