DataTransferItemList.length
The read-only length
property of the
DataTransferItemList
interface returns the number of items currently in
the drag item list.
Value
The number of drag data items in the list, or 0 if the list is empty or disabled. The
drag item list is considered to be disabled if the item list's
DataTransfer
object is not associated with a drag data store.
Examples
This example shows the use of the length
property.
JavaScript
function dragstart_handler(ev) {
console.log("dragStart");
// Add this element's id to the drag payload so the drop handler will
// know which element to add to its tree
var dataList = ev.dataTransfer.items;
dataList.add(ev.target.id, "text/plain");
// Add some other items to the drag payload
dataList.add("<p>... paragraph ...</p>", "text/html");
dataList.add("http://www.example.org","text/uri-list");
}
function drop_handler(ev) {
console.log("Drop");
ev.preventDefault();
var data = ev.dataTransfer.items;
// Loop through the dropped items and log their data
for (var i = 0; i < data.length; i++) {
if ((data[i].kind == 'string') && (data[i].type.match('^text/plain'))) {
// This item is the target node
data[i].getAsString(function (s){
ev.target.appendChild(document.getElementById(s));
});
} else if ((data[i].kind == 'string') && (data[i].type.match('^text/html'))) {
// Drag data item is HTML
data[i].getAsString(function (s){
console.log("... Drop: HTML = " + s);
});
} else if ((data[i].kind == 'string') && (data[i].type.match('^text/uri-list'))) {
// Drag data item is URI
data[i].getAsString(function (s){
console.log("... Drop: URI = " + s);
});
}
}
}
function dragover_handler(ev) {
console.log("dragOver");
ev.preventDefault();
// Set the dropEffect to move
ev.dataTransfer.dropEffect = "move"
}
function dragend_handler(ev) {
console.log("dragEnd");
var dataList = ev.dataTransfer.items;
// Clear any remaining drag data
dataList.clear();
}
HTML
<div>
<p id="source" ondragstart="dragstart_handler(event);" ondragend="dragend_handler(event);" draggable="true">
Select this element, drag it to the Drop Zone and then release the selection to move the element.</p>
</div>
<div id="target" ondrop="drop_handler(event);" ondragover="dragover_handler(event);">Drop Zone</div>
CSS
div {
margin: 0em;
padding: 2em;
}
#source {
color: blue;
border: 1px solid black;
}
#target {
border: 1px solid black;
}
Result
Specifications
Specification |
---|
HTML Standard # dom-datatransferitemlist-length-dev |
Browser compatibility
BCD tables only load in the browser