d4l3k/WebSync

// Polyfill for non-standard webkit method scrollIntoViewIfNeeded by Hubert SABLONNIERE @hsablonniere
if (!Element.prototype.scrollIntoViewIfNeeded) {
    Element.prototype.scrollIntoViewIfNeeded = function(centerIfNeeded) {
        centerIfNeeded = arguments.length === 0 ? true : !! centerIfNeeded;
        var parent = this.parentNode,
            parentComputedStyle = window.getComputedStyle(parent, null),
            parentBorderTopWidth = parseInt(parentComputedStyle.getPropertyValue('border-top-width')),
            parentBorderLeftWidth = parseInt(parentComputedStyle.getPropertyValue('border-left-width')),
            overTop = this.offsetTop - parent.offsetTop < parent.scrollTop,
            overBottom = (this.offsetTop - parent.offsetTop + this.clientHeight - parentBorderTopWidth) > (parent.scrollTop + parent.clientHeight),
            overLeft = this.offsetLeft - parent.offsetLeft < parent.scrollLeft,
            overRight = (this.offsetLeft - parent.offsetLeft + this.clientWidth - parentBorderLeftWidth) > (parent.scrollLeft + parent.clientWidth),
            alignWithTop = overTop && !overBottom;
        if ((overTop || overBottom) && centerIfNeeded) {
            parent.scrollTop = this.offsetTop - parent.offsetTop - parent.clientHeight / 2 - parentBorderTopWidth + this.clientHeight / 2;
        }
        if ((overLeft || overRight) && centerIfNeeded) {
            parent.scrollLeft = this.offsetLeft - parent.offsetLeft - parent.clientWidth / 2 - parentBorderLeftWidth + this.clientWidth / 2;
        }
        if ((overTop || overBottom || overLeft || overRight) && !centerIfNeeded) {
            this.scrollIntoView(alignWithTop);
        }
    };
}