SpinBox

Input with buttons to increase or decrease a value
Demo: A NumberSpinBox for incrementing/decrementing a numeric value

Overview

The SpinBox is useful in situations where a value can be expressed on a continuous range. It is often used for entering numbers, a task handled by the more specialized NumberSpinBox subclass, but is more general than the corresponding <input type="number"> in native HTML.

You could create a SpinBox capable of accepting units:

Demo: Custom SpinBox that accepts units like px for pixels

You can use a SpinBox to allow the user to increment and decrement a value that's not a simple decimal number, or to manipulate a value in a different numeric representation system:

Demo: Custom SpinBox that manipulates Roman numbers

Like all Elix base components, you can also customize SpinBox to accommodate your own design system:

Demo: SpinBox extended for a custom design system

Like the standard <input type="number">, SpinBox lets the user increment/decrement with both mouse/touch as well as the Up/Down hardware keys.

Usage

import SpinBox from "elix/define/SpinBox.js";
const spinBox = new SpinBox();

A SpinBox makes sense if the allowable values form a continuous range. If only discrete elements from a range are permissible, a ComboBox or DropdownList might be more appropriate.

See also

API

Class hierarchy:

The element defines the following shadow parts:

  • button: the up and down buttons, default type is button element
  • down-button: the down button
  • input: the text input portion of the spin box, default type is input element
  • up-button: the up button

defaultState property

The default state for the component. This can be extended by mixins and classes to provide additional default state.

Type: PlainObject

Defined by ReactiveMixin

delegatesFocus property

Returns true if the component is delegating its focus.

A component using DelegateFocusMixin will always have this property be true unless a class takes measures to override it.

Type: boolean

Default: true

Defined by DelegateFocusMixin

disabled property

True if the component is disabled, false (the default) if not.

The value of this property will be reflected to the disabled attribute so that it can be referenced in CSS. Note that this non-native implementation of the disabled attribute will not trigger the :disabled CSS pseudo-class, so your style rules will have to reference the presence or absence of the disabled attribute. That is, instead of writing

my-component:disabled { ... }

write this instead

my-component[disabled] { ... }

Like the native disabled attribute, this attribute is boolean. That means that it's existence in markup sets the attribute, even if set to an empty string or a string like "false".

Type: boolean

Default: false

Defined by DisabledMixin

disabledchange event

Raised when the disabled property changes.

Defined by DisabledMixin

form property

The ID of the form element with which this element is associated, or null if the element is not associated with any form. This is provided for consistency with the native HTML form property.

Type: string

Defined by FormElementMixin

goDown() method

Invoked when the user wants to go/navigate down. The default implementation of this method does nothing.

Defined by KeyboardDirectionMixin

goEnd() method

Invoked when the user wants to go/navigate to the end (e.g., of a list). The default implementation of this method does nothing.

Defined by KeyboardDirectionMixin

goLeft() method

Invoked when the user wants to go/navigate left. The default implementation of this method does nothing.

Defined by KeyboardDirectionMixin

goRight() method

Invoked when the user wants to go/navigate right. The default implementation of this method does nothing.

Defined by KeyboardDirectionMixin

goStart() method

Invoked when the user wants to go/navigate to the start (e.g., of a list). The default implementation of this method does nothing.

Defined by KeyboardDirectionMixin

goUp() method

Invoked when the user wants to go/navigate up. The default implementation of this method does nothing.

Defined by KeyboardDirectionMixin

ids property

A convenient shortcut for looking up an element by ID in the component's Shadow DOM subtree.

Example: if component's template contains a shadow element <button id="foo">, you can use the reference this[ids].foo to obtain the corresponding button in the component instance's shadow tree. The ids property is simply a shorthand for getElementById, so this[ids].foo is the same as this[shadowRoot].getElementById('foo').

Type: object

Defined by ShadowTemplateMixin

keydown() method

See the symbols documentation for details.

Defined by KeyboardMixin

name property

The name of the form field that will be filled with this element's value. This is an analogue of the standard HTML name property.

Type: string

Defined by FormElementMixin

render(changed) method

Render the indicated changes in state to the DOM.

The default implementation of this method does nothing. Override this method in your component to update your component's host element and any shadow elements to reflect the component's new state. See the rendering example.

Be sure to call super in your method implementation so that your component's base classes and mixins have a chance to perform their own render work.

Parameters:

  • changed: ChangedFlagsdictionary of flags indicating which state members have changed since the last render

Defined by ReactiveMixin

renderChanges() method

Render any pending component changes to the DOM.

This method does nothing if the state has not changed since the last render call.

ReactiveMixin will invoke this method following a setState call; you should not need to invoke this method yourself.

This method invokes the internal render method, then invokes the rendered method.

Defined by ReactiveMixin

rendered(changed) method

Perform any work that must happen after state changes have been rendered to the DOM.

The default implementation of this method does nothing. Override this method in your component to perform work that requires the component to be fully rendered, such as setting focus on a shadow element or inspecting the computed style of an element. If such work should result in a change in component state, you can safely call setState during the rendered method.

Be sure to call super in your method implementation so that your component's base classes and mixins have a chance to perform their own post-render work.

Parameters:

  • changed: ChangedFlags

Defined by ReactiveMixin

select() method

Selects all the text.

See the standard select documentation for details.

Defined by DelegateInputSelectionMixin

selectionEnd property

The end index of the selected text.

See the standard input element documentation for details.

Defined by DelegateInputSelectionMixin

selectionStart property

The beginning index of the selected text.

See the standard input element documentation for details.

Defined by DelegateInputSelectionMixin

setRangeText() method

Replaces a range of text.

See the standard setRangeText documentation for details.

Defined by DelegateInputSelectionMixin

setSelectionRange() method

Sets the start and end positions of the current text selection.

See the standard setSelectionRange documentation for details.

Defined by DelegateInputSelectionMixin

setState(changes) method

Update the component's state by merging the specified changes on top of the existing state. If the component is connected to the document, and the new state has changed, this returns a promise to asynchronously render the component. Otherwise, this returns a resolved promise.

Parameters:

  • changes: PlainObjectthe changes to apply to the element's state

Returns: Promise - resolves when the new state has been rendered

Defined by ReactiveMixin

state property

The component's current state.

The returned state object is immutable. To update it, invoke internal.setState.

It's extremely useful to be able to inspect component state while debugging. If you append ?elixdebug=true to a page's URL, then ReactiveMixin will conditionally expose a public state property that returns the component's state. You can then access the state in your browser's debug console.

Type: PlainObject

Defined by ReactiveMixin

stateEffects(state, changed) method

Ask the component whether a state with a set of recently-changed fields implies that additional second-order changes should be applied to that state to make it consistent.

This method is invoked during a call to internal.setState to give all of a component's mixins and classes a chance to respond to changes in state. If one mixin/class updates state that it controls, another mixin/class may want to respond by updating some other state member that it controls.

This method should return a dictionary of changes that should be applied to the state. If the dictionary object is not empty, the internal.setState will apply the changes to the state, and invoke this stateEffects method again to determine whether there are any third-order effects that should be applied. This process repeats until all mixins/classes report that they have no additional changes to make.

See an example of how ReactiveMixin invokes the stateEffects to ensure state consistency.

Parameters:

  • state: PlainObjecta proposal for a new state
  • changed: ChangedFlagsthe set of fields changed in this latest proposal for the new state

Returns: PlainObject

Defined by ReactiveMixin

type property

The "type" of the form field, provided for consistency with the native HTML type property. The value of this property will be the same as the HTML tag name registered for the custom element.

Type: string

Defined by FormElementMixin

value property

The text entered in the spin box.

Type: string

Default: ""