I have an igCombo that has a button in the header template.  The button has an "onclick='handleClick(this)'" specified.  How can I get a reference to the igCombo instance inside of the "handleClick()" function without using an id of the igCombo?

function igComboHeaderSelectAllHandler(e) {
 // use "e" to get a relative reference to the igCombo instance
}


// igCombo options
{
        dataSource: igComboDataSource,
        textKey: "Name",
        valueKey: "Name",
        allowCustomValue: false,
        autoComplete: true,
        enableClearButton: false,
        itemTemplate: "<span title=\"${Name}\"\>${Name}</span>",
        headerTemplate: "<div><input type='button' value='Select All' onclick='igComboHeaderSelectAllHandler(this)' /></div>",
        multiSelection: {
            enabled: true,
            showCheckboxes: true,
            itemSeparator: ','
        }