你可以使用点号(.)来修改 JSON 对象的 - 在线编辑器

          <p>修改 JSON 对象的值。</p>

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

<script>
  var myObj, i, x = "";
  myObj = {
    "name": "mifengjc",
    "alexa": 10000,
    "sites": {
      "site1": "www.mifengjc.com",
      "site2": "m.mifengjc.com",
      "site3": "c.mifengjc.com"
    }
  }
  myObj.sites.site1 = "www.google.com";
  for (i in myObj.sites) {
    x += myObj.sites[i] + "<br>";
  }
  document.getElementById("demo").innerHTML = x;
</script>
        