ondragstart Event

Fires on the source object when the user starts to drag a text selection or selected object.

dhtml语法

Inline HTML <ELEMENT ondragstart = "handler" ... > All platforms
Event property object.ondragstart = handler JScript only
object.ondragstart = GetRef("handler") Visual Basic Scripting Edition (VBScript) 5.0 or later only
Named script <SCRIPT FOR = object EVENT = ondragstart> Internet Explorer only

Event Information

Bubbles Yes
Cancels Yes
To invoke Drag the selected text or object.
Default action Calls the associated event handler.

Event Object Properties

Although event handlers in the DHTML Object Model do not receive parameters directly, a handler can query an event object for data.
available properties
altKey Sets or retrieves a value that indicates the state of the ALT key.
altLeft Sets or retrieves a value that indicates the state of the left ALT key.
cancelBubble Sets or retrieves whether the current event should bubble up the hierarchy of event handlers.
clientX Sets or retrieves the x-coordinate of the mouse pointer's position relative to the client area of the window, excluding window decorations and scroll bars.
clientY Sets or retrieves the y-coordinate of the mouse pointer's position relative to the client area of the window, excluding window decorations and scroll bars.
ctrlKey Sets or retrieves the state of the CTRL key.
altKey Sets or retrieves a value that indicates the state of the ALT key.
altLeft Sets or retrieves a value that indicates the state of the left ALT key.
dataTransfer Provides access to predefined clipboard formats for use in drag-and-drop operations.
offsetX Sets or retrieves the x-coordinate of the mouse pointer's position relative to the object firing the event.
offsetY Sets or retrieves the y-coordinate of the mouse pointer's position relative to the object firing the event.
returnValue Sets or retrieves the return value from the event.
screenX Retrieves the x-coordinate of the mouse pointer's position relative to the user's screen.
screenY Sets or retrieves the y-coordinate of the mouse pointer's position relative to the user's screen.
shiftLeft Retrieves the state of the left SHIFT key.
srcElement Sets or retrieves the object that fired the event.
type Sets or retrieves the event name from the event object.
x Sets or retrieves the x-coordinate, in pixels, of the mouse pointer's position relative to a relatively positioned parent element.
y Sets or retrieves the y-coordinate, in pixels, of the mouse pointer's position relative to a relatively positioned parent element.

Remarks

The ondragstart event is the first to fire when the user starts to drag the mouse. It is essential to every drag operation, yet is just one of several source events in the data transfer object model. Source events use the setdata method of the datatransfer object to provide information about data being transferred. source events include ondragstart, ondrag, and ondragend.
when dragging anything other than an img object, some text to be dragged must be selected.

Examples

This example uses event bubbling to handle the ondragstart event at the body level.
<body ondragstart="alert(event.srcelement.tagname)">
<INPUT TYPE=text VALUE="Select and drag this text">
<SPAN>Select and drag this text</SPAN>
<TEXTAREA>Select and drag this text</TEXTAREA>
</BODY>
This feature requires Microsoft® Internet Explorer 5 or later. Click the following icon to install the latest version. Then reload this page to view the sample.
This example shows the order of event firing for drag-and-drop events.
<HEAD>
<SCRIPT>
function ShowResults(){
var oNewOption;
// Code for dynamically adding options to a select.
}
function ShowResults()
{				// Information about the events
// and what object fired them.
arg = event.type + "  fired by  " + event.srcElement.id;
oNewOption = new Option();
oNewOption.text = arg;
oResults.add(oNewOption,0);
}
</SCRIPT>
</HEAD>
<BODY>
<P>Source events are wired up to this text box.</P>
<INPUT ID=txtDragOrigin VALUE="Text to Drag"
ondragstart="ShowResults()"
ondrag="ShowResults()"
ondragend="ShowResults()"
>
<P>Target events are bound to this text box.</P>
<INPUT ID=txtDragDestination VALUE="Drag Destination"
ondragenter="ShowResults()"
ondragover="ShowResults()"
ondragleave="ShowResults()"
ondrop="ShowResults()"
>
<SELECT ID=oResults SIZE=30>
<OPTION>List of Events Fired
</SELECT>
</BODY>
This feature requires Microsoft® Internet Explorer 5 or later. Click the following icon to install the latest version. Then reload this page to view the sample.

是否符合公共标准

There is no public standard that applies to this event.

Applies To

A, ACRONYM, ADDRESS, AREA, B, BDO, BIG, BLOCKQUOTE, BODY, CAPTION, CENTER, CITE, CODE, CUSTOM, DD, DEL, DFN, DIR, DIV, DL, document, DT, EM, FIELDSET, FONT, FORM, hn, HR, I, IMG, INPUT type=button, INPUT type=checkbox, INPUT type=file, INPUT type=image, INPUT type=password, INPUT type=radio, INPUT type=reset, INPUT type=submit, INPUT type=text, KBD, LABEL, LI, LISTING, MAP, MARQUEE, MENU, nextID, NOBR, OBJECT, OL, P, PLAINTEXT, PRE, Q, RT, RUBY, S, SAMP, SMALL, SPAN, STRIKE, STRONG, SUB, SUP, TABLE, TBODY, TD, TEXTAREA, TFOOT, TH, THEAD, TR, TT, U, UL, VAR, XMP

更多语法参考

about dhtml data transfer, ondrop