<!DOCTYPE html>
<html>
<head>
<meta charset="UTF-8">
<title></title>
</head>
<body>
<button type="button" id="btn">反选</button>
<ul>
<li>
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
<input type="checkbox" />
</li>
</ul>
<script>
//实现反选
var oBtn = document.getElementById("btn")
var oInput = document.getElementsByTagName("input")
// oInput[0].checked=true
oBtn.onclick = function() {
for(var i = 0; i < oInput.length; i++) {
oInput[i].checked =!oInput[i].checked
}
}
</script>
</body>
</html>