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我正在为学校做这项作业，但在我找不到的地方有一个逻辑。我几乎 100% 确定它setElemId()是应该设置和返回元素 id 的函数，但它一直没有返回任何内容，当我href为快速链接设置时，它只是设置#而不是ID.

HTML

<body>
   <div id="page">
      <div id="logo"><img src="hlogo.jpg" alt="Historic Documents" /></div>
      <div id="logosub">Department of History<br />Midwest University</div>

      <div id="doc">
         <h1 id="doctitle">The Federalist Papers <br />No. 10</h1>
         <p id="docsubtitle">The Union as a Safeguard Against 
            Domestic Faction and Insurrection<br />From the New York Packet. Friday, 
            November 23, 1787.</p>

         <p id="intro">To the people of the state of New York:</p>

         <p id="firstp">Among the numerous advantages promised by a well-constructed 
            Union, none deserves to be more accurately developed than its 
            tendency to break and control the violence of faction. The friend of 
            distresses under which we labor have been erroneously charged on the 
         </p>

         <p>By a <dfn id="firstkey">faction</dfn>, I understand a number of 
            citizens, whether amounting to a majority or a minority of the whole, 
            interest, adversed to the rights of other citizens, or to the permanent 
            and aggregate interests of the community.</p>

         <p>The other point of difference is, the greater number of citizens and 
            extent of territory which may be brought within the compass of 
            the former than in the latter. The smaller the society, the fewer 
         </p>

      </div>
   </div>
</body>
</html>

Javascript

function addEvent(object, evName, fnName, cap) {
   if (object.attachEvent)
       object.attachEvent("on" + evName, fnName);
   else if (object.addEventListener)
       object.addEventListener(evName, fnName, cap);
}

addEvent(window, "load", makeKeyWordBox, false);

// Returns an array of Text
function makeElemList(elem)
{
    var elemList = document.getElementsByTagName('dfn');
    var elemTextArr = new Array();

    for(var i = 0; i < elemList.length; i++)
        elemTextArr[i] = elemList[i].innerText.toLowerCase();

    elemTextArr.sort();
    return elemTextArr;
}

// Searches for and returns a single ID
function setElemId(elem, elemText)
{
    var elemList = document.getElementsByTagName(elem);
    var elemTextArr = new Array();
    var elemId;

    for(var i = 0; i < elemList.length; i++)
    {
        elemTextArr[i] = elemList[i].innerText.toLowerCase();

        if(elemTextArr[i] == elemText)
        {
            if(elemList[i].id = null)
            {
                elemId = elemText + i;
                elemList[i].setAttribute('id', elemId);
                return elemId;
            }
            else
            {
                alert(elemList[i].id);
                elemId = elemList[i].id;
                return elemId;
            }
        }
    }
}

function makeKeyWordBox()
{
    var keywords = makeElemList('dfn');
    var historyDoc = document.getElementById('doc');
    var keywordBoxTitle = document.createElement('h1');
        keywordBoxTitle.innerText = "Keywords";
    var keywordBox = document.createElement('div');
        keywordBox.id = "keywords";
        keywordBox.appendChild(keywordBoxTitle);
    var ulList = document.createElement('ul');
        keywordBox.appendChild(ulList);

    for(var i = 0; i < keywords.length; i++)
    {
        var linkId = setElemId('dfn', keywords[i]);
        var newListItem = document.createElement('li');
        var newLink = document.createElement('a');
            newLink.innerText = keywords[i];
            newLink.href = "#" + linkId;
        newListItem.appendChild(newLink);
        ulList.appendChild(newListItem);
    }

    historyDoc.insertBefore(keywordBox, historyDoc.firstChild);
}
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2 回答 2

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您似乎正在搜索关键字的完全匹配。由于您的所有元素都不包含您要查找的关键字（而是包含文本），因此没有匹配项。

相反，尝试if( elemTextArr[i].indexOf(elemText) > -1)

所以请注意，您似乎没有将搜索词转换为小写，所以如果我输入大写字母，我将不会得到任何匹配。

于 2012-12-07T23:37:02.433 回答
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“它会命中 if 语句，但它要么 a) 总是为 false (就像它已经设置了一个 ID)”

尝试改变：

if(elemList[i].id = null)

到：

if(!elemList[i].id)

您正在分配idtonull而不是将其与null（您在使用or=时使用）进行比较，然后 the会将其评估为（falsy）并每次都进入案例。=====ifnullelse

null另外，我认为您无论如何都不想与之进行比较，因为id未设置的将不会null（当我尝试时，未设置id的是空字符串，""）。更容易使用!运算符来测试是否id“虚假”。

于 2012-12-08T05:36:33.227 回答