This specific scenario will be perfect using html button and call javascript function in on click event to handle the select/deselect rows by checking/un-checking the IsRowChecker.

First, we’ll need an input button.

<input id="Button1" type="button" value="Select/Deselect All Rows" onclick="return Button1_onclick()" />

Next, in OnClick event of the button, we need to get the input element of the IsRowChecker; and then simply call “click()” method of the checkbox input element to trigger ‘wgCheckBoxHeaderClick(this)’ function. The ‘wgCheckBoxHeaderClick(this)’ function is the onclick function of the IsRowChecker checkbox input element.

function Button1_onclick() {
    var WebGrid1 = ISGetObject("WebGrid1");
    var rowCheckerElm = WebGrid1.RootTable.GetElement(WG40.COLHEADER, WG40.HTMLTABLE).cells[1].childNodes[0].childNodes[0].childNodes[0];

    rowCheckerElm.click();

    return true;
}

Please let us know whether this helps or not.