转换数组到字符串 -toString()

<p id="demo">点击按钮将数组转为字符串并返回。</p>

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

<script>

  function myFunction() {

    var fruits = ["Banana", "Orange", "Apple", "Mango"];

    var str = fruits.toString();

    var x = document.getElementById("demo");

    x.innerHTML = str;

  }

</script>