在本例中，我们将执行一次全局替换，每当 "Microsoft" 被找到，它就被替换为 "Mifengjc"

<p>单击按钮将段落中“Microsoft”替换成“Mifengjc”：</p>

<p id="demo">Visit Microsoft!</p>

<button onclick="myFunction()">点我</button>

<script>

  function myFunction() {

    var str = document.getElementById("demo").innerHTML;

    var n = str.replace("Microsoft", "Mifengjc");

    document.getElementById("demo").innerHTML = n;

  }

</script>