source: Dev/trunk/src/client/dijit/form/_ToggleButtonMixin.js

define([
        "dojo/_base/declare", // declare
        "dojo/dom-attr" // domAttr.set
], function(declare, domAttr){

        // module:
        //              dijit/form/_ToggleButtonMixin

        return declare("dijit.form._ToggleButtonMixin", null, {
                // summary:
                //              A mixin to provide functionality to allow a button that can be in two states (checked or not).

                // checked: Boolean
                //              Corresponds to the native HTML `<input>` element's attribute.
                //              In markup, specified as "checked='checked'" or just "checked".
                //              True if the button is depressed, or the checkbox is checked,
                //              or the radio button is selected, etc.
                checked: false,

                // aria-pressed for toggle buttons, and aria-checked for checkboxes
                _aria_attr: "aria-pressed",

                _onClick: function(/*Event*/ evt){
                        var original = this.checked;
                        this._set('checked', !original); // partially set the toggled value, assuming the toggle will work, so it can be overridden in the onclick handler
                        var ret = this.inherited(arguments); // the user could reset the value here
                        this.set('checked', ret ? this.checked : original); // officially set the toggled or user value, or reset it back
                        return ret;
                },

                _setCheckedAttr: function(/*Boolean*/ value, /*Boolean?*/ priorityChange){
                        this._set("checked", value);
                        var node = this.focusNode || this.domNode;
                        if(this._created){ // IE is not ready to handle checked attribute (affects tab order)
                                // needlessly setting "checked" upsets IE's tab order
                                if(domAttr.get(node, "checked") != !!value){
                                        domAttr.set(node, "checked", !!value); // "mixed" -> true
                                }
                        }
                        node.setAttribute(this._aria_attr, String(value)); // aria values should be strings
                        this._handleOnChange(value, priorityChange);
                },

                postCreate: function(){ // use postCreate instead of startup so users forgetting to call startup are OK
                        this.inherited(arguments);
                        var node = this.focusNode || this.domNode;
                        if(this.checked){
                                // need this here instead of on the template so IE8 tab order works
                                node.setAttribute('checked', 'checked');
                        }
                },

                reset: function(){
                        // summary:
                        //              Reset the widget's value to what it was at initialization time

                        this._hasBeenBlurred = false;

                        // set checked state to original setting
                        this.set('checked', this.params.checked || false);
                }
        });
});