<p>点击按钮以索引为键值的方式循环数组 "cars", 开始的索引值为 2</p>

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

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

<script>

function myFunction() {

    var cars = ["BMW", "Volvo", "Saab", "Ford"];

    var i = 2;

    var len = cars.length;

    var text = "";

    for (; i < len; i++) {

        text += cars[i] + "<br>";

    }

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

}

</script>

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