我有一段代码，其中包含一些窗口警报消息。工作正常。但是，如果删除警报语句，程序将进入无限循环。对我来说这很奇怪。

有人可以帮助我确定代码问题吗？

function countSwaps(arr) {

    let notVisited = {},swaps = 0;
    for (let i = 0; i < arr.length; i++) {
        notVisited[i] = true;
    }

    while (Object.keys(notVisited).length) {
        alert("main pass");
        let nextPos,currentPos = Object.keys(notVisited)[0];
        while (arr[currentPos] !== parseInt(currentPos+1)) {
            nextPos = arr[currentPos] - 1;
            [arr[currentPos],arr[nextPos]] = [arr[nextPos],arr[currentPos]];

            swaps+= 1;
            alert("Swap " + arr[currentPos] + " and " + arr[nextPos] + "\n");
            delete notVisited[nextPos];
        }
        delete notVisited[currentPos];
    }
    return swaps;
}
console.log(countSwaps([2,3,4,1,5]));