你可以使用索引值来修改数组 - 在线编辑器

          <p>修改 JSON 对象数组值。</p>

<p id="demo"></p>

<script>
  var myObj, i, x = "";
  myObj = {
    "name": "网站",
    "num": 3,
    "sites": ["Google", "Mifengjc", "Taobao"]
  };
  myObj.sites[1] = "Github";
  for (i in myObj.sites) {
    x += myObj.sites[i] + "<br>";
  }
  document.getElementById("demo").innerHTML = x;
</script>
        