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Fluid Component API

This page describes the Fluid standard conventions for defining components of different types. Following these standards to a greater or lesser extent will result in differing levels of support and interoperability with other parts of the Fluid Framework.

General recommendations

A Fluid component should be

  • DOM agnostic: components should work with a variety of markup, and not make assumptions about the structure of the DOM. Any assumptions made by the component should be expressed in the form of selectors, supported by the framework's DOM Binder.
  • Accessible: components should be equally usable with either the mouse or the keyboard. ARIA roles and states should be used to ensure support for assistive technologies. Use the framework's keyboard-a11y plugin and the jQuery UI ARIA support.
  • this-free: Avoid use of JavaScript's this and new keywords, in favour of units and that-ism .
  • Testable: Components should be readily testable using the jqUnit testing toolkit. Tests should be provided for all component functions.

Basic component API

This section describes the basic level of support required for a Fluid component.

Creating a component

A component should provide a creator function that is responsible for creating a new instance of the component. This function should accept at least two arguments:

  1. The container for the component. This should always be the first argument.
  2. An options object containing configuration options for the component. This should always be the last argument.


The first argument to a component's creator function represents a container for the component.

It is assumed that

  • A container is a jQueryable element; a string representing a selector, a DOM element, or a jQuery.
  • All markup belonging to the component, and all DOM nodes that the component will directly modify are nested below the container node
  • When this DOM node is hidden, all visible evidence of the existence of the component will also be hidden.


The last argument to a component creator will be options, a JavaScript object specifying the details of configuration of the component. Some of the structure of options is standardised; at bare minimum, it should contain the following properties:

Property path




hash of strings

a set of selector strings which, when scoped to the container passed as the first argument, will nominate parts of the DOM which are "of interest" to the component. For information on naming conventions, see Class Name Conventions.

styles (optional)

hash of strings

Unlike selectors, these need to be globally namespaced, since they are expected to be referenced in style sheets to apply styles to parts of the component markup. For information on naming conventions, see Class Name Conventions.

mergePolicy (optional)


A "policy object" whose keys are EL paths into the options structure itself, and which encodes any special instructions to the framework to be followed when merging the user's options against any registered defaults. Documented on its own page at Options Merging for Infusion Components

listeners (optional)

hash of functions

a set of listener funtions to attach to supported events.

strings (optional)

hash of strings

a set of strings to inject into the user interface.

options and defaults

The options structure is laid out almost identically to a "master options structure" which is registered using the fluid.defaults utility. This structure defines the default values to be used in the case that implementors do not fill in an option. For example, for a component named inlineEdit, the defaults registration might begin like this:

    fluid.defaults("inlineEdit", {  
        selectors: {
            text: ".text",
            editContainer: ".editContainer",
            edit: ".edit"

This example defines default selectors for the Inline Edit component. As the componenent's creator starts up, it will merge together the user's instance options with the version from defaults using jquery.extend to produce its runtime options.

Example of a component creator function

// A component creator function:
fluid.myComponent = function(container, options) {


Runtime structure of a Fluid component

The that for a Fluid component, once it is created, will contain the following structure at top level:




A DOM node holding the component (identical to the container argument to the component, see description above)


The "merged" set of options to the component (see description of defaults above)


event firers for any events that the component supports (see Infusion Event System for information)

Runtime structure of a "model-bearing" component

A Fluid component may be structured around a "model" (in the MVC sense) - conditions on "reasonable models" are described on Component Model Interactions and API. Model-bearing components have more requirements on the runtime structure of their that - in addition to the two basic members above, they will also possess the following:




A "reasonable model" for the component (that is, one that consists of pure data)


A function which can accept zero arguments, which when invoked will refresh all of the visible structure of the component to bring it in step with the current state of model


A structure as dispensed from fluid.event.getEventFirer - this allows listeners to subscribe to updates to the model, as well as update events to be fired.