代码示例:(标识:jsck_state_for_s3_om)
<!DOCTYPE html>
<html>
<body>

<p>在本例中,我们省略了最后一个参数,并在循环内增加了计数器变量。</p>

<p>单击这个按钮可按升序循环遍历数组的索引。</p>

<button onclick="myFunction()">试一试</button>

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

<script>
function myFunction() {
  var cars = ["BMW", "Volvo", "Saab", "Ford"];

  var i = 0;
  var len = cars.length;
  var text = "";

  for (; i < len;) {
    text += cars[i] + "<br>";
    i++;
  }
  document.getElementById("demo").innerHTML = text;
}
</script>

</body>
</html>
运行结果: