Custom ComboBox class

ComboBoxJson.js

Ext.ns('IbwUi.controls');

IbwUi.controls.ComboBoxJSON = Ext.extend(Ext.form.ComboBox, {

    url: '',
    root: '',
    valueField: 'id',
    displayField: 'name',
    listWidth: 200,
    width: 200,


    initComponent: function () {

        var comboStoreJson = new Ext.data.JsonStore({
            idProperty: 'id',
            autoDestroy: true,
            autoLoad: true,
            root: this.root,
            fields: this.fields || [{
                name: 'id',
                type: 'int'
            }, {
                name: 'name',
                type: 'string'
            }],
            sortInfo: {
                field: this.displayField,
                direction: 'ASC'
            },
            proxy: new Ext.data.ScriptTagProxy({
                api: {
                    read: this.url
                }
            })
        });

        var config = {
            autoSelect: true,
            store: comboStoreJson,
            displayField: this.displayField,
            valueField: this.valueField,
            mode: 'remote',
            forceSelection: true,
            minChars: 1,
            triggerAction: 'all',
            lastQuery: '',
            typeAhead: true,
            typeAheadDelay: 50,
            lazyRender: true,
            lastQuery: '',
            value: this.value,
            listWidth: this.width + 200,
            width: this.width,
            listeners: {}
        };

        Ext.apply(this, config);

        IbwUi.controls.ComboBoxJSON.superclass.initComponent(this);

    }
});

Ext.reg("ibwComboJson", IbwUi.controls.ComboBoxJSON);