为什么 mouseout 和 mouseleave 总是触发

Question

我真的不明白为什么 p 元素总是隐藏（因此 mouseout 总是被触发）：

const canvas = document.querySelector("canvas");
const infoBox = document.querySelector("#info-box")
canvas.addEventListener("mousemove", evt => {
    evt.preventDefault()
    infoBox.style.display="block"
    infoBox.style.position="absolute"
    infoBox.style.top= evt.clientY+"px"
    infoBox.style.left=evt.clientX+"px"
    console.log("moved")
})
canvas.addEventListener("mouseout", evt => {
    evt.preventDefault()
    infoBox.style.display="none"
    console.log("exit")
}, false)

canvas{
    border-width: 0px;
    border-color:#212121;
    background-color: blue;
}

<canvas></canvas>
<div id="info-box" style="display: none;"><p>Hello</p></div>

Answer 1

每次 info-box 出现时都会退出。在#info-boxdiv上加上一个偏移量意味着鼠标认为它没有离开canvas.

const canvas = document.querySelector("canvas");
const infoBox = document.querySelector("#info-box");
const mouseOffset = 2;

canvas.addEventListener("mousemove", evt => {
  evt.preventDefault()
  infoBox.style.display = "block"
  infoBox.style.position = "absolute"
  infoBox.style.top = evt.clientY + mouseOffset + "px" // add an offset here
  infoBox.style.left = evt.clientX + mouseOffset + "px" // and here
  console.log("moved")
})
canvas.addEventListener("mouseout", evt => {
  evt.preventDefault()
  infoBox.style.display = "none"
  console.log("exit")
}, false)

canvas {
  border-width: 0px;
  border-color: #212121;
  background-color: blue;
}

<canvas></canvas>
<div id="info-box" style="display: none;">
  <p>Hello</p>
</div>

为什么 mouseout 和 mouseleave 总是触发

Why is mouseout and mouseleave always firing

html

javascript

mouseevent

mouseout