moodle/theme/boost/templates/gradereport_history/user_button.mustache

<div class="{{classes}}">
    <div method="{{method}}" action="{{url}}" id="{{formid}}">
        {{#params}}
            <input type="hidden" name="{{name}}" value="{{value}}">
        {{/params}}
        <input type="button" class="btn btn-secondary selectortrigger"
            id="{{id}}"
            title={{#quote}}{{tooltip}}{{/quote}}
            value={{#quote}}{{label}}{{/quote}}
            {{#disabled}}disabled{{/disabled}}>
    </div>
</div>
{{#hasactions}}
    {{#js}}
        require(['core/yui'], function(Y) {
            {{#actions}}
                Y.on('{{event}}', {{{jsfunction}}}, '#{{id}}', null{{#jsfunctionargs}}, {{{jsfunctionargs}}}{{/jsfunctionargs}});
            {{/actions}}
        });
    {{/js}}
{{/hasactions}}