<!DOCTYPE html>
<html>
<head>
<meta charset="utf-8">
<title></title>
</head>
<body>
<button onclick="stopColor()">停止切換</button>
<script>
var myVar = setInterval(function(){ setColor() }, 50);
function setColor() {
var x = document.body;
x.style.backgroundColor = x.style.backgroundColor == "yellow" ? "pink" : "yellow";
}
function stopColor() {
clearInterval(myVar);
}
</script>
</body>
</html>