Parameter von vaadin-button (html) to java-script

Flow
1

Hi,
Vaadin 14
I want to transfer parameters from vaadin-button (html) to Java-script

HTML:

<vaadin-button id="buttonExcelExport" on-click="onClickButtonExcelExport"  theme="icon" title=[[plmExcelExport]
]> 
    	<iron-icon icon="vaadin:table" class = "button-icon" ></iron-icon>
	</vaadin-button>

Parameter: [[productDetails.keyname] ]

java-script

onClickButtonExcelExport (event) {
            	window.location.href = 'gui/xls/?keyname='+event.target.dataset.keyname;
            }

		How can I do it?