type EventNames = 'click' | 'scroll' | 'mousemove';
function handleEvent(ele: Element, event: EventNames) {
　　// do something
}
 
handleEvent(document.getElementById('hello'), 'scroll'); // 没问题
handleEvent(document.getElementById('world'), 'dbclick'); // 报错，event 不能为 'dbclick'
 
// index.ts(7,47): error TS2345: Argument of type '"dbclick"' is not assignable to parameter of type 'EventNames'.