HTML5 drag & drop elements created by javascript:

Question

When i try to drag and drop elements which are normaly created by the html everything is ok, but when i try to drag and drop elements which are generated by javascript returns me this error:

Uncaught TypeError: Cannot read property 'parentNode' of null

My code: js for drag and drop:

var id1;
var name;
function drag(ev) {
    name = document.getElementById(ev.target.id).parentNode.id;
    ev.dataTransfer.setData("text", name);
    id1 = document.getElementById(name).parentNode.id;
}
function drop(ev) {
    var id2 = ev.target.id;
    if(id1 === id2 + '1'){
        ev.preventDefault();
        var data = ev.dataTransfer.getData("text");
        ev.target.appendChild(document.getElementById(data));
        //Add info to arrays
        holders["\"" + id2 + "\": ["].push("{\"place_holder\":\"" + id2 + "\", \"name\":\"" + name + "\"}", ", ");
    }
}

function allowDrop(ev) {
    ev.preventDefault();
}

html example generated by the javascript:

<div id="screen">
    <div id="menu_items" ondrop="drag(event)" ondragover="allowDrop(event)"></div>
    <div id="items1" ondrop="drag(event)" ondragover="allowDrop(event)"></div></div>
<div id="options">
    <div class="menu_items1">
        <div id="m_div_img10" class="img0" draggable="true" ondragstart="drag(event)">                  <img src="./images/example.jpg" alt="example.jpg">
            <span class="tooltip"><img src="./images/tip.png"></span></div><div id="m_div_img21" class="img1" draggable="true" ondragstart="drag(event)">
            <img src="./images/example.jpg" alt="example.jpg">
                <span class="tooltip">
            <img src="./images/tip.png">
        </span>
    </div>
    </div>
    <div class="items1"></div>
</div>

Example of the way of generating the html:

var items = document.createElement('div');
items.id = "options";
document.getElementsByTagName('body')[0].appendChild(items);
var innerDivElem = document.createElement('div');
.
.
.
innerDivElem.id = obj[i][t].name + t;
innerDivElem.className = "img" + t;
innerDivElem.draggable='true';
innerDivElem.setAttribute('ondragstart', 'drag(event)');
inContainerDiv.appendChild(innerDivElem);

Answer 1

I fixed it by adding the fuctions inside these, and instead of geting the id by ev.target.id i am getting it by this.id:

innerDivElement.addEventListener( "dragstart" , function(e){
    drag(e);
});

and it become:

innerDivElem.addEventListener( "dragstart" , function drag(ev){
    name = document.getElementById(this.id).id;
    ev.dataTransfer.setData("text", name);
    id1 = document.getElementById(name).parentNode.id;
});