Button

A push button on an HTML form.

Client-side object
Implemented inJavaScript 1.0 JavaScript 1.1: added type property; added onBlur and onFocus event handlers; added blur and focus methods. JavaScript 1.2: added handleEvent method.

The HTML

INPUT tag, with "button" as the value of the TYPE attribute. For a given form, the JavaScript runtime engine creates appropriate Button objects and puts these objects in the elements array of the corresponding Form object. You access a Button 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 Button object on a form looks as follows:

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

The Button object is a custom button that you can use to perform an action you define. The button executes the script specified by its onClick event handler.

Property Summary

PropertyDescription
formSpecifies the form containing the Button object.
nameReflects the NAME attribute.
type>Reflects the TYPE> attribute.
valueReflects the VALUE attribute.

Metodos

MethodDescription
blurRemoves focus from the button.
clickSimulates a mouse-click on the button.
focusGives focus to the button.
handleEventInvokes the handler for the specified event.
In addition, this object inherits the watch and unwatch methods from Object

Ejemplos

The following example creates a button named calcButton. The text "Calculate" is displayed on the face of the button. When the button is clicked, the function calcFunction is called.

<INPUT TYPE="button" VALUE="Calculate" NAME="calcButton"
   onClick="calcFunction(this.form)">

See also

Form Reset Submit


blur

Removes focus from the button.

Method ofButton
Implemented in

JavaScript 1.0

Syntax

blur()

Parameters

None

Examples

The following example removes focus from the button element userButton:

userButton.blur()
This example assumes that the button is defined as

<INPUT TYPE="button" NAME="userButton">

See also

Button.focus


click

Simulates a mouse-click on the button, but does not trigger the button's onClick event handler.
Method of

Button

Implemented inJavaScript 1.0

Syntax

click()

Parameters

None.

Security

Submitting a form to a mailto: or news: URL requires the UniversalSendMail privilege. For information on security, see the Client-Side JavaScript Guide


Focus

Navigates to the button and gives it focus.

Method of Button
Implemented inJavaScript 1.0

Syntax

focus()

Parameters

None.

See also

Button.blur


form

An object reference specifying the form containing the button.

Property ofButton
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.

Examples

Example 1. In the following example, the form myForm contains a Text object and a button. When the user clicks the button, the value of the Text object is set to the form's name. The button's onClick event handler uses this.form to refer to the parent form, myForm.

<FORM NAME="myForm">
Form name:<INPUT TYPE="text" NAME="text1" VALUE="Beluga">
<P>
<INPUT NAME="button1" TYPE="button" VALUE="Show Form Name"
   onClick="this.form.text1.value=this.form.name">
</FORM>
Example 2. The following example shows a form with several elements. When the user clicks button2, the function showElements displays an alert dialog box containing the names of each element on the form myForm.

function showElements(theForm) {
   str = "Form Elements of form " + theForm.name + ": \n "
   for (i = 0; i < theForm.length; i++)
      str += theForm.elements[i].name + "\n"
   alert(str)
}
</script>
<FORM NAME="myForm">
Form name:<INPUT TYPE="text" NAME="text1" VALUE="Beluga">
<P>
<INPUT NAME="button1" TYPE="button" VALUE="Show Form Name"
   onClick="this.form.text1.value=this.form.name">
<INPUT NAME="button2" TYPE="button" VALUE="Show Form Elements"
   onClick="showElements(this.form)">
</FORM>
The alert dialog box displays the following text:

JavaScript Alert:
Form Elements of form myForm:
text1
button1
button2
Example 3. The following example uses an object reference, rather than the this keyword, to refer to a form. The code returns a reference to myForm, which is a form containing myButton.
document.myForm.myButton.form

See also

Form


handleEvent

Invokes the handler for the specified event.

Method of

Button

Implemented in

Syntax

handleEvent(event)

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 button's name.

Property of

Button
Implemented in

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. Changing the name property overrides this setting.

Do not confuse the name property with the label displayed on a button. The value property specifies the label for the button. The name property is not displayed on the screen; it is used to refer programmatically to the object.

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 Button 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>")
   }
}
In the following example, the first statement creates a window called netscapeWin. The second statement displays the value "netscapeHomePage" in the Alert dialog box, because "netscapeHomePage" is the value of the windowName argument of netscapeWin.

netscapeWin=window.open("http://home.netscape.com","netscapeHomePage")alert(netscapeWin.name)

See also

Button.value


type

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

Property ofButton
Read-only
Implemented inJavaScript 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 button's VALUE attribute.

Property of

Button

Read-only on Mac and UNIX; modifiable on Windows
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

This string is displayed on the face of the button.

The value property is read-only for Macintosh and UNIX systems. On Windows, you can change this property.

When a VALUE attribute is not specified in HTML, the value property is an empty string.

Do not confuse the value property with the name property. The name property is not displayed on the screen; it is used to refer programmatically to the objects.

Examples

The following function evaluates the value property of a group of buttons and displays it in the msgWindow window:

function valueGetter() {
   var msgWindow=window.open("")
   msgWindow.document.write("submitButton.value is " +
      document.valueTest.submitButton.value + "<BR>")
   msgWindow.document.write("resetButton.value is " +
      document.valueTest.resetButton.value + "<BR>")
   msgWindow.document.write("helpButton.value is " +
      document.valueTest.helpButton.value + "<BR>")
   msgWindow.document.close()
}
This example displays the following values:
Query Submit
Reset
Help
The previous example assumes the buttons have been defined as follows:

<INPUT TYPE="submit" NAME="submitButton">
<INPUT TYPE="reset" NAME="resetButton">
<INPUT TYPE="button" NAME="helpButton" VALUE="Help">

Manual JS v1.0
Enrique Garrido-Lecca Risco
Proyecto Perú Ruteable