reaction add event code example
Example 1: react button onclick
<button onClick={sayHello}>Click</button>
Example 2: react event listener
onClick onContextMenu onDoubleClick onDrag onDragEnd onDragEnter onDragExit
onDragLeave onDragOver onDragStart onDrop onMouseDown onMouseEnter onMouseLeave
onMouseMove onMouseOut onMouseOver onMouseUp