


How do I transfer data during a drag-and-drop operation using the dataTransfer object?
Jun 24, 2025 am 12:57 AMIn the drag-and-drop operation, the dataTransfer object implements data transfer through setData() and getData(). 1. Use setData() to set data in the dragstart event. You need to specify the MIME type and content, such as 'text/plain' and 'text/uri-list'; 2. Use getData() to extract data according to the same type in the drop event, and you can also use the type attribute to determine the available types; 3. You can control the drag effect prompts through effectAllowed and dropEffect, such as copying or moving; 4. When dragging multiple projects, you can use JSON format to encapsulate. When dragging files, you can obtain the file list through the files attribute to realize the upload function. Mastering these basic usages can enable flexible drag-and-drop interactions in web pages.
In the drag-and-drop operation, dataTransfer
object is the core of implementing data transfer. It allows you to exchange information between dragging the source and dropping the target. To complete data transmission, the key is to use setData()
and getData()
methods correctly.
Set drag data: use setData()
When you start dragging an element, you can access dataTransfer
object through dragstart
event and use setData()
method to set the data to be passed. This method accepts two parameters: the data type (usually MIME type) and the actual data content.
For example:
element.addEventListener('dragstart', function(event) { event.dataTransfer.setData('text/plain', 'This is dragged data'); });
Common types include:
-
'text/plain'
—— Plain text -
'text/uri-list'
—— URL list -
'text/html'
—— HTML content
You can choose the appropriate type according to your needs, such as when dragging an image, you can use 'text/uri-list'
to pass the image link.
Get drag data: use getData()
In the drop
event where the target is placed, the data set previously can be obtained through dataTransfer.getData()
. Note that you have to extract the data using the same type as in setData()
.
The sample code is as follows:
dropTarget.addEventListener('drop', function(event) { const data = event.dataTransfer.getData('text/plain'); console.log(data); // Output: This is dragged data});
If you are not sure what type the user is dragging, you can try multiple types to get values, or combine types
attribute to determine the supported data format:
for (let type of event.dataTransfer.types) { console.log(type); // View available types}
Effect tips during dragging and dropping
In addition to transferring data, you can also use dataTransfer.effectAllowed
and dropEffect
to control visual feedback during dragging, such as copying, moving, or linking operations.
For example, set allowed operations in dragstart
:
event.dataTransfer.effectAllowed = 'copyMove';
Specify the specific effect in dragover
or drop
:
event.dataTransfer.dropEffect = 'copy';
This way the browser will display different cursor styles based on these settings, allowing the user to know whether the copy or move operation is currently in progress.
Tips
- If you want to drag multiple items, you can combine them into strings (such as JSON format) and send them through
setData()
. - Different browsers may have slightly different support for certain MIME types, so please pay attention to compatibility when testing.
- When dragging and dropping a file,
dataTransfer
can also directly obtain the file list throughfiles
attribute, which is suitable for the upload function.
Basically that's it. Once you master the basic usage of dataTransfer
, you can realize flexible drag-and-drop interaction in the web page.
The above is the detailed content of How do I transfer data during a drag-and-drop operation using the dataTransfer object?. For more information, please follow other related articles on the PHP Chinese website!

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