用数组的元素组成字符串 - join()

<p id="demo">点击按钮将数组作为字符串输出。</p>

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

<script>

  function myFunction() {

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

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

    x.innerHTML = fruits.join();

  }

</script>