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FileUpload

A file upload element on an HTML form. A file upload element lets the user supply a file as input.

Client-side object

Implemented in

JavaScript 1.0

JavaScript 1.1: added type property

JavaScript 1.2: added handleEvent method.

Created by

The HTML INPUT tag, with "file" as the value of the TYPE attribute. For a given form, the JavaScript runtime engine creates appropriate FileUpload objects and puts these objects in the elements array of the corresponding Form object. You access a FileUpload object by indexing this array. You can index the array either by number or, if supplied, by using the value of the NAME attribute.

Event handlers

Description

A FileUpload object on a form looks as follows:

A FileUpload object is a form element and must be defined within a FORM tag.

Property Summary

Property Description
form

Specifies the form containing the FileUpload object.

name

Reflects the NAME attribute.

type

Reflects the TYPE attribute.

value

Reflects the current value of the file upload element's field; this corresponds to the name of the file to upload.

Method Summary

Method Description
blur

Removes focus from the object.

focus

Gives focus to the object.

handleEvent

Invokes the handler for the specified event.

select

Selects the input area of the file upload field.

In addition, this object inherits the watch and unwatch methods from Object.

Examples

The following example places a FileUpload object on a form and provides two buttons that let the user display current values of the name and value properties.

<FORM NAME="form1">
File to send: <INPUT TYPE="file" NAME="myUploadObject">
<P>Get properties<BR>
<INPUT TYPE="button" VALUE="name"
   onClick="alert('name: ' + document.form1.myUploadObject.name)">
<INPUT TYPE="button" VALUE="value"
   onClick="alert('value: ' + document.form1.myUploadObject.value)"><BR>
</FORM>

See also

Text


blur

Removes focus from the object.

Method of

FileUpload

Implemented in

JavaScript 1.0

Syntax

blur()

Parameters

None

See also

FileUpload.focus, FileUpload.select


focus

Navigates to the FileUpload field and give it focus.

Method of

FileUpload

Implemented in

JavaScript 1.0

Syntax

focus()

Parameters

None

See also

FileUpload.blur, FileUpload.select


form

An object reference specifying the form containing the object.

Property of

FileUpload

Read-only

Implemented in

JavaScript 1.0

Description

Each form element has a form property that is a reference to the element's parent form. This property is especially useful in event handlers, where you might need to refer to another element on the current form.


handleEvent

Invokes the handler for the specified event.

Syntax

handleEvent(event)

Method of

FileUpload

Implemented in

JavaScript 1.2

Parameters

event

The name of an event for which the object has an event handler.

Description

For information on handling events, see the Client-Side JavaScript Guide.


name

A string specifying the name of this object.

Property of

FileUpload

Read-only

Implemented in

JavaScript 1.0

Security

JavaScript 1.1: This property is tainted by default. For information on data tainting, see the Client-Side JavaScript Guide.

Description

The name property initially reflects the value of the NAME attribute. The name property is not displayed on-screen; it is used to refer to the objects programmatically.

If multiple objects on the same form have the same NAME attribute, an array of the given name is created automatically. Each element in the array represents an individual Form object. Elements are indexed in source order starting at 0. For example, if two Text elements and a FileUpload element on the same form have their NAME attribute set to "myField", an array with the elements myField[0], myField[1], and myField[2] is created. You need to be aware of this situation in your code and know whether myField refers to a single element or to an array of elements.

Examples

In the following example, the valueGetter function uses a for loop to iterate over the array of elements on the valueTest form. The msgWindow window displays the names of all the elements on the form:

newWindow=window.open("http://home.netscape.com")
function valueGetter() {
   var msgWindow=window.open("")
   for (var i = 0; i < newWindow.document.valueTest.elements.length; i++) {
      msgWindow.document.write(newWindow.document.valueTest.elements[i].name + "<BR>")
   }
}

select

Selects the input area of the file upload field.

Method of

FileUpload

Implemented in

JavaScript 1.0

Syntax

select()

Parameters

None

Description

Use the select method to highlight the input area of a file upload field. You can use the select method with the focus method to highlight a field and position the cursor for a user response. This makes it easy for the user to replace all the text in the field.

See also

FileUpload.blur, FileUpload.focus


type

For all FileUpload objects, the value of the type property is "file". This property specifies the form element's type.

Property of

FileUpload

Read-only

Implemented in

JavaScript 1.1

Examples

The following example writes the value of the type property for every element on a form.

for (var i = 0; i < document.form1.elements.length; i++) {
   document.writeln("<BR>type is " + document.form1.elements[i].type)
}

value

A string that reflects the VALUE attribute of the object.

Property of

FileUpload

Read-only

Implemented in

JavaScript 1.0

Security

JavaScript 1.1: This property is tainted by default. For information on data tainting, see the Client-Side JavaScript Guide.

JavaScript 1.2: Setting a file upload widget requires the UniversalFileRead privilege. For information on security, see the Client-Side JavaScript Guide.

Description

Use the value property to obtain the file name that the user typed into a FileUpload object.


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Last Updated: 11/16/98 12:56:21

Copyright (c) 1998 Netscape Communications Corporation