Snap Links Lite 1.2.4 User JS

// created from Snap Links Lite 1.2.4
// https://chrome.google.com/webstore/detail/snap-links-lite/idmmhhijggcmbeejedibpdcahpkneegg?hl=en

var ox = 0;
var oy = 0;
var onDown = false;
var onWork = false;
var obj = false;
var objSub = [];
var objSubLink = [];
var blockContextMenu = false;

var visibleOnly = 1;
var button = 2;
var reverse = 0;

function eventMouseDown(e)
{
    if(e.button != button)
        return true;
    e.stopPropagation();
    e.preventDefault();
    onDown = true;
    blockContextMenu = false;
    ox = e.pageX;
    oy = e.pageY;
}

function getBoxObjectForXY(element)
{
    var x = 0;
    var y = 0;
    var parent = element;
    while ( parent ) {
        x += parent.offsetLeft;
        y += parent.offsetTop;
        parent = parent.offsetParent;
    }

    parent = element;
    while ( parent &&
    parent != document.body &&
    parent != document.documentElement ) {
        if ( parent.scrollLeft  )
            x -= parent.scrollLeft;
        if ( parent.scrollTop )
            y -= parent.scrollTop;
        parent = parent.parentNode;
    }

    return { x:x, y:y};
}
function isVisible(obj)
{
    var parent = obj;
    while ( parent ) {
        if(window.getComputedStyle(parent, null).display == 'none')
            return false;
        if(window.getComputedStyle(parent, null).visibility == 'hidden')
            return false;
        if(parseInt(window.getComputedStyle(parent, null).zIndex) < 0)
            return false;
        parent = parent.offsetParent;
    }
    return true;
}
function getBoxObjectFor(obj)
{
    var xy = getBoxObjectForXY(obj);
    return {
        x:xy.x
        ,y:xy.y
        ,width:obj.offsetWidth
        ,height:obj.offsetHeight
    };
}
function eventMouseMove(e)
{
    if(!onDown)
        return true;
    e.stopPropagation();
    e.preventDefault();
    if(!onWork)
    {
        if(Math.abs(ox - e.clientX) > 3
            && Math.abs(oy - e.clientY) > 3)
        {
            onWork = true;
            obj = document.createElement("div");
            (document.body || document.documentElement).appendChild(obj);
            obj.style.position = "absolute";
            obj.style.left = ox + "px";
            obj.style.top = oy + "px";
            obj.style.border = "1px dotted green";
        }
    }
    if(onWork)
    {
        if(e.pageX > ox)
            obj.style.width = (e.pageX - ox) + "px";
        else
        {
            obj.style.left = e.pageX + "px";
            obj.style.width = (ox - e.pageX) + "px";
        }
        if(e.pageY > oy)
            obj.style.height = (e.pageY - oy) + "px";
        else
        {
            obj.style.top = e.pageY + "px";
            obj.style.height = (oy - e.pageY) + "px";
        }
        while(objSub.length)
            obj.removeChild(objSub.pop());
        objSubLink = [];

        var tsize = getBoxObjectFor(obj);

        for(i = 0; i < document.links.length; i++){
            var link = document.links[i];
            lsize = getBoxObjectFor(link);

            if(link.href && link.href.indexOf('javascript:') >= 0)
                continue;
            if(!lsize || lsize.y + lsize.height < tsize.y || tsize.y + tsize.height < lsize.y)
                continue;
            if(!lsize || lsize.x + lsize.width < tsize.x || tsize.x + tsize.width < lsize.x)
                continue;
            if(visibleOnly && !isVisible(link))
                continue;

            var lover = document.createElement("div");
            lover.style.position = "absolute";
            lover.style.zIndex = "65535";
            lover.style.left = (lsize.x - tsize.x - 2) + "px";
            lover.style.top = (lsize.y - tsize.y - 2) + "px";
            lover.style.width = lsize.width + "px";
            lover.style.height = lsize.height + "px";
            lover.style.border = "1px solid red";

            objSub.push(lover);
            objSubLink.push(link.href);

            obj.appendChild(lover);
        }
    }
}

function eventMouseUp(e)
{
    if(e.button != button)
        return true;

    if(onWork)
    {
        e.stopPropagation();
        e.preventDefault();

        for(var k in objSubLink)
            for(var j in objSubLink)
                if(k != j && objSubLink[k] == objSubLink[j])
                    objSubLink[j] = false;

        if(reverse)
            objSubLink.reverse();
        for(var k in objSubLink)
            if(objSubLink[k])
                window.open(objSubLink[k]);

        blockContextMenu = true;
        obj.parentNode.removeChild(obj);
        objSub = [];
        objSubLink = [];
    }

    obj = onDown = onWork = false;
}
function eventContextmenu(e)
{
    if(button == 2)
        if(blockContextMenu)
            e.preventDefault();
}
function eventMouseDrag(e)
{
    if(e.button != button)
        return true;
}

window.addEventListener("mousedown", eventMouseDown, true);
window.addEventListener("mousemove", eventMouseMove, true);
window.addEventListener("mouseup", eventMouseUp, true);
window.addEventListener("mousedrag", eventMouseDrag, true);
document.addEventListener("contextmenu", eventContextmenu, true);