<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<meta http-equiv="X-UA-Compatible" content="ie=edge">
<title>Document</title>
</head>
<body>
<p id="p1"></p>
<p id="p2"></p>
<p id="p3"></p>
</body>
</html>
<script>
var a=[2,6,4];
var b=a;
var c=a.concat();
b[0]=99;
document.getElementById("p1").innerText=a;
document.getElementById("p2").innerText=b;
document.getElementById("p3").innerText=c;
</script>
网页显示
99,6,4
99,6,4
2,6,4