mouseenter / mouseleave

gistfile1.js

function bindMouseLeave(obj, fn) {
    if (obj.attachEvent) {
        obj.attachEvent('onmouseleave', function() {
            fn.call(obj, window.event);
        });
    } else {
        obj.addEventListener('mouseout', function(e) {
            var rt = e.relatedTarget;
            if (rt !== obj && !isContain(obj, rt)) {
                fn.call(obj, e);
            }
        },
        false);
    }
}
function bindMouseEnter(obj, fn) {
    if (obj.attachEvent) {
        obj.attachEvent('onmouseenter', function() {
            fn.call(obj, window.event);
        });
    } else {
        obj.addEventListener('mouseover', function(e) {
            var rt = e.relatedTarget;
            if (rt !== obj && !isContain(obj, rt)) {
                fn.call(obj, e);
            }
        },
        false);
    }
}

isContain

function isContain(a, b) {
    try {
        return a.contains ? a != b && a.contains(b) : !!(a.compareDocumentPosition(b) & 16);
    }catch (e) {}
}