btns[0].onmousedown=function () { console.log("鼠标按下") }

btns[0].onmouseup=function () { console.log("鼠标抬起") }

btns[0].onmousemove=function () { console.log("鼠标移动") }

btns[0].onmouseenter=function () { console.log("鼠标进入") }

btns[0].onmouseover=function () { console.log("鼠标进入over") }

btns[0].onmouseleave=function () { console.log("鼠标移出2") }

btns[0].onmouseout=function () { console.log("鼠标移出") }

btns[0].onmousewheel=function () { console.log("鼠标滚动") }

btns[0].onmousedblclick=function () { console.log("鼠标双击") }