Question

I’m currently making a Drag-and-Drop javascript engine. I want to make one class (.drag) the bare-minimum the element must have to be “drag-able”. Currently my .drag class in css has some extra stuff in it and I want to split it into two classes. However, when I split the class, the object I wish to drag is no longer “drag-able”.

Currently:

.drag {
    position: absolute;
    width: 100px;
    height: 100px;
    background: red;
    cursor:move;
    -webkit-user-select: none;
    -moz-user-select: none;
    user-select: none;
}

And I would like to have two classes:

.drag {
    position: absolute;
    -webkit-user-select: none;
    -moz-user-select: none;
    user-select: none;
}

.square {
    width: 100px;
    height: 100px;
    background: red;
    cursor:move;
}

HTML changes from:

<p class="drag">Thing One</p>
<p class="drag">Thing Two</p>

To:

<p class="drag square">Thing One</p>
<p class="drag square">Thing Two</p>

And here is the javascript:

// JavaScript Document

var posX;
var posY;
var element;
var currentPos;

document.addEventListener("mousedown", drag, false);

function drag(event) {
    if(event.target.className == "drag") {
        element = event.target;
        element.style.zIndex="100";
        currentPos = findPos(element);
        posX = event.clientX -currentPos.x; //-parseInt(element.offsetLeft);
        posY = event.clientY -currentPos.y; //-parseInt(element.offsetTop);
        document.addEventListener("mousemove", move, false);
    }
}

function move(event) {

    if (typeof(element.mouseup) == "undefined")
        document.addEventListener("mouseup", drop, false);
    //Prevents redundantly adding the same event handler repeatedly

    element.style.left = event.clientX - posX + "px";
    element.style.top = event.clientY - posY + "px";
}

function drop() {
    element.style.zIndex="1";
    document.removeEventListener("mousemove", move, false);
    document.removeEventListener("mouseup", drop, false);
    //alert("DEBUG_DROP");
}    

function findPos(obj) { // Donated by `lwburk` on StackOverflow
    var curleft = curtop = 0;
    if (obj.offsetParent) {
        do {
            curleft += obj.offsetLeft;
            curtop += obj.offsetTop;
        } while (obj = obj.offsetParent);
        return { x: curleft, y: curtop };
    }
}

Why won’t the elements drag when I split the class? How do I fix it?

Thank you so much for reading and helping! I greatly appreciate it.

Answer 1

Your conditional has event.target.className == "drag" but this is no longer true as now it == "drag square". What you want is something like:

event.target.className.search(/\bdrag\b/) > -1

for your conditional.