Question

我正在尝试在Javascript中对数组进行排序，但出现了问题，我无法弄清楚原因。问题是输出是错误的，因为在调用myFunc函数后，一些数组元素被标记为“未定义”并且没有值。我期望看到的元素按降序排序。但不是这样，我得到了一些带有“undefined”字样的字段。

这里是Javascript代码：

var arr = [1, 123, 2, 321, 341, 2];
/*var arr = [];
arr[0] = 1;
arr[1] = 123;
arr[2] = 2;
arr[3] = 321;
arr[4] = 341;
arr[5] = 2;*/

function selectionsort(){
    var n = 6;
    for(var i=0; i<n-1; i++)
    {
        var index = i;
        for(var j=i+1; j<n; j++)
        {
            if(arr[index]<arr[j])
            {
                index = j;
            }
        }
        console.log(arr[index]);
        if(index != i)
        {
            var temp = arr[j];
            arr[i] = arr[index];
            arr[index] = temp;
        }
    }
}

function initFunc()
{
        document.getElementById("asdf").innerHTML = arr[0];
        document.getElementById("asdf1").innerHTML = arr[1];
        document.getElementById("asdf2").innerHTML = arr[2];
        document.getElementById("asdf3").innerHTML = arr[3];
        document.getElementById("asdf4").innerHTML = arr[4];
        document.getElementById("asdf5").innerHTML = arr[5];

        document.getElementById("demoto+0").innerHTML = arr[0];
        document.getElementById("demoto+1").innerHTML = arr[1];
        document.getElementById("demoto+2").innerHTML = arr[2];
        document.getElementById("demoto+3").innerHTML = arr[3];
        document.getElementById("demoto+4").innerHTML = arr[4];
        document.getElementById("demoto+5").innerHTML = arr[5]; 
}

function myFunc(){  
        document.getElementById("demoto+0").innerHTML = arr[0];
        document.getElementById("demoto+1").innerHTML = arr[1];
        document.getElementById("demoto+2").innerHTML = arr[2];
        document.getElementById("demoto+3").innerHTML = arr[3];
        document.getElementById("demoto+4").innerHTML = arr[4];
        document.getElementById("demoto+5").innerHTML = arr[5];     

        selectionsort();

        document.getElementById("asdf").innerHTML = arr[0];
        document.getElementById("asdf1").innerHTML = arr[1];
        document.getElementById("asdf2").innerHTML = arr[2];
        document.getElementById("asdf3").innerHTML = arr[3];
        document.getElementById("asdf4").innerHTML = arr[4];
        document.getElementById("asdf5").innerHTML = arr[5];
}

这是被操纵的html页面：

<button type="button" onclick="myFunc()">click</button>
<div class="wrapper">
            <div class="order">
            <ul id="boxes">
            <li><div id="demoto+0" class="transperant"></div></li>
            <li><div id="demoto+1" class="transperant"></div></li>
            <li><div id="demoto+2" class="transperant"></div></li>
            <li><div id="demoto+3" class="transperant"></div></li>
            <li><div id="demoto+4" class="transperant"></div></li>
            <li><div id="demoto+5" class="transperant"></div></li>
            </ul>
            </div>
        <br>
            <div class="order2">
            <ul id = "boxes">
            <li><div id="asdf" class="transperant">S</div></li>
            <li><div id="asdf1" class="transperant">S</div></li>
            <li><div id="asdf2" class="transperant">S</div></li>
            <li><div id="asdf3" class="transperant">S</div></li>
            <li><div id="asdf4" class="transperant">S</div></li>
            <li><div id="asdf5" class="transperant">S</div></li>
            </ul>
            </div>
        </div>

Answer 1

你真的需要重新发明轮子吗？只需使用

[1, 123, 2, 321, 341, 2].sort(function(a,b){return a-b;});

Answer 2

您可以在数组上使用sort（）方法。像这样： arr.sort（）

在Javascript中排序数组时出现意外错误

2 个答案: