javascript - getElementsByClassName 不是 Firefox 中的函数

Question

我在 GoodReads 上的阅读书架混合了已出版和未出版的书籍，因此很难找到已出版的内容可供阅读。我想我可以组合一个 GreaseMonkey 脚本来更改尚未出版的书籍的条目背景。

到目前为止，这是我整理的：

// ==UserScript==
// @name        Unpublished Lowlighter
// @description Makes the background of books not yet published on the Goodreads to-read shelf grey.
// @include     http://www.goodreads.com/*
// ==/UserScript==

function dateColor() {
    var books = document.getElementsByClassName('bookalike review');
    for (var book in books) {
        var dateString = book
                        .getElementsByClassName('field date_pub')
                        .getElementsByClassName('value')
                        .textContent;
        var date = new Date(dateString);
        var today = new Date();
        if (date > today) {
            book.style.backgroundColor('Lightgrey');
        }
    }
}

dateColor();

问题是它不起作用。当我尝试在暂存器中运行脚本时，它给了我错误：Exception: book.getElementsByClassName is not a function

我的印象是 Firefox 支持getElementsByClassName并且您可以在结果上运行它getElementsByClassName以获取子元素。我哪里错了？

<tr>编辑：这是表格中一个的 HTML 片段。我没有发布这个开始的原因是它真的很冗长：

<tr id="review_265364012" class="bookalike review">
  <td class="field checkbox" style="display: none"><label>checkbox</label><div class="value">      <input id="checkbox_review_265364012" name="reviews[265364012]" value="265364012" type="checkbox">
</div></td>  <td class="field position"><label>position</label><div class="value">        <div class="reorderControls">
            <a class="actionLink" href="#" id="loading_link_434018960" method="post" onclick="$(this).hide(); $('loading_anim_434018960').show(); $('hidden_link_434018960').simulate('click');; return false;"><img alt="up" src="http://www.goodreads.com/assets/up_arrow-7957f2bae9c3456ec7359ad79b000652.gif" title="move book up"></a><img alt="Loading-trans" class="loading" id="loading_anim_434018960" src="http://www.goodreads.com/assets/loading-trans-3e04cd6ed6ad31063972e688820d7866.gif" style="display:none"><a href="/shelf/move_up/174788201?redirect_url=%2Freview%2Flist%2F4111865%3Fformat%3Dhtml%26page%3D1%26shelf%3Dto-read" class="actionLink" data-method="post" id="hidden_link_434018960" rel="nofollow" style="display: none"><img alt="up" src="http://www.goodreads.com/assets/up_arrow-7957f2bae9c3456ec7359ad79b000652.gif" title="move book up"></a>
          <img src="/assets/loading.gif" class="position_loading" style="display: none">
          <input id="positions_174788201" name="positions[174788201]" value="5" type="text">
          <script type="text/javascript">
//<![CDATA[
      var newTip = new Tip($('positions_174788201'), "            <nobr>\n              <a class=\"button\" href=\"#\" onclick=\"savePositionChanges(4111865); return false;\">Save position changes<\/a> &nbsp;\n              <a href=\"#\" onclick=\"$(\'positions_174788201\').prototip.hide(); return false;\">close<\/a>\n            <\/nobr>\n", { style: 'creamy', stem: 'leftMiddle', hook: { tip: 'leftMiddle', target: 'rightMiddle' }, offset: { x: 5, y: 5 }, hideOn: 'imaginaryelement', showOn: 'click', width: 'auto', hideOthers: true });
      $('positions_174788201').observe('prototip:shown', function() {
        if (this.up('#box')) {
          $$('div.prototip')[0].setStyle({zIndex: $('box').getStyle('z-index')});
        } else {
          $$('div.prototip')[0].setStyle({zIndex: 6000});
        }
      });

//]]>
</script>            <a class="actionLink" href="#" id="loading_link_434206980" method="post" onclick="$(this).hide(); $('loading_anim_434206980').show(); $('hidden_link_434206980').simulate('click');; return false;"><img alt="down" src="http://www.goodreads.com/assets/down_arrow-61b0e7292c02b1dcfd3f75a7f9b6b7ad.gif" title="move book down"></a><img alt="Loading-trans" class="loading" id="loading_anim_434206980" src="http://www.goodreads.com/assets/loading-trans-3e04cd6ed6ad31063972e688820d7866.gif" style="display:none"><a href="/shelf/move_down/174788201?redirect_url=%2Freview%2Flist%2F4111865%3Fformat%3Dhtml%26page%3D1%26shelf%3Dto-read" class="actionLink" data-method="post" id="hidden_link_434206980" rel="nofollow" style="display: none"><img alt="down" src="http://www.goodreads.com/assets/down_arrow-61b0e7292c02b1dcfd3f75a7f9b6b7ad.gif" title="move book down"></a>
        </div>
</div></td>  <td class="field cover"><label>cover</label><div class="value">      <a href="/book/show/12074927-the-fractal-prince"><img alt="The Fractal Prince (The Quantum Thief Trilogy #2)" src="http://photo.goodreads.com/books/1311105989s/12074927.jpg" title="The Fractal Prince (The Quantum Thief Trilogy #2)"></a>
</div></td>  <td class="field title"><label>title</label><div class="value">    <a href="/book/show/12074927-the-fractal-prince" title="The Fractal Prince (The Quantum Thief Trilogy #2)">
      The Fractal Prince
        <span class="darkGreyText">(The Quantum Thief Trilogy #2)</span>
</a></div></td>  <td class="field author"><label>author</label><div class="value">      <a href="/author/show/2768002.Hannu_Rajaniemi">Rajaniemi, Hannu</a>
</div></td>  <td class="field isbn" style="display: none"><label>isbn</label><div class="value">    
</div></td>  <td class="field isbn13" style="display: none"><label>isbn13</label><div class="value">    
</div></td>  <td class="field asin" style="display: none"><label>asin</label><div class="value">    
</div></td>  <td class="field num_pages" style="display: none"><label>num pages</label><div class="value">      <span class="greyText">unknown</span>
</div></td>  <td class="field avg_rating"><label>avg rating</label><div class="value">    3.67
</div></td>  <td class="field num_ratings" style="display: none"><label>num ratings</label><div class="value">    9
</div></td>  <td class="field date_pub"><label>date pub</label><div style="background: none repeat scroll 0% 0% Lightgrey;" class="value">      Sep 27, 2012
</div></td>  <td class="field date_pub_edition" style="display: none"><label>date pub edition</label><div class="value">      <span class="greyText">unknown</span>
</div></td>    <td class="field rating"><label>my rating</label><div class="value">
    <span class="stars" id="stars12074927_4111865" onmouseout="mouseOutStars('12074927')"><a rel="nofollow"><img alt="didn't like it " class="star" id="star12074927_0" onclick="submitStars('12074927', 0, '/review/rate/12074927?rating=1', 4111865);  return false;" onmouseover="checkStars('12074927', 0)" src="/assets/layout/gr_orange_star_inactive.png" title="didn't like it" height="15" width="15"></a><a rel="nofollow"><img alt="it was ok " class="star" id="star12074927_1" onclick="submitStars('12074927', 1, '/review/rate/12074927?rating=2', 4111865);  return false;" onmouseover="checkStars('12074927', 1)" src="/assets/layout/gr_orange_star_inactive.png" title="it was ok" height="15" width="15"></a><a rel="nofollow"><img alt="liked it " class="star" id="star12074927_2" onclick="submitStars('12074927', 2, '/review/rate/12074927?rating=3', 4111865);  return false;" onmouseover="checkStars('12074927', 2)" src="/assets/layout/gr_orange_star_inactive.png" title="liked it" height="15" width="15"></a><a rel="nofollow"><img alt="really liked it " class="star" id="star12074927_3" onclick="submitStars('12074927', 3, '/review/rate/12074927?rating=4', 4111865);  return false;" onmouseover="checkStars('12074927', 3)" src="/assets/layout/gr_orange_star_inactive.png" title="really liked it" height="15" width="15"></a><a rel="nofollow"><img alt="it was amazing " class="star" id="star12074927_4" onclick="submitStars('12074927', 4, '/review/rate/12074927?rating=5', 4111865);  return false;" onmouseover="checkStars('12074927', 4)" src="/assets/layout/gr_orange_star_inactive.png" title="it was amazing" height="15" width="15"></a></span><script language="javascript" type="text/javascript">starRatings[ratingIndex++] = [ '12074927', -1]; checkStars('12074927', -1);</script>
    <span id="reviewMessage12074927_4111865"></span>
    <span id="successMessage12074927_4111865"></span>
</div></td><td class="field shelves"><label>shelves</label><div class="value">    <span id="shelfList4111865_12074927"><span id="shelf_174788201"><a href="http://www.goodreads.com/review/list/4111865?shelf=to-read" class="shelfLink" title="View all books in Johan's to-read shelf.">to-read</a></span></span><br><a class="shelfChooserLink smallText" href="#" onclick="window.shelfChooser.summon(event, {bookId: 12074927, chosen: [&quot;to-read&quot;]}); return false;">[edit]</a>
</div></td><td class="field review" style="display: none"><label>review</label><div class="value">    <span class="greyText">None</span>
    <a class="floatingBoxLink smallText" href="#" onclick="reviewEditor.summon(this, 12074927, 'review', {value: null}); return false;">[edit]</a>
  <div class="clear"></div>
</div></td><td class="field notes" style="display: none"><label>notes</label><div class="value">      <span class="greyText">None</span>
      <a class="floatingBoxLink smallText" href="#" onclick="reviewEditor.summon(this, 12074927, 'notes', {value: null}); return false;">[edit]</a>
</div></td><td class="field recommender" style="display: none"><label>recommender</label><div class="value">    <span class="greyText">none</span>
</div></td><td class="field comments" style="display: none"><label>comments</label><div class="value">  <a href="/review/show/265364012">0</a>
</div></td><td class="field votes" style="display: none"><label>votes</label><div class="value">  <a href="/rating/voters/265364012?resource_type=Review">0</a>
</div></td><td class="field read_count" style="display: none"><label># times read</label><div class="value">    0
</div></td><td class="field date_started" style="display: none"><label>date started</label><div class="value">    <span class="greyText">not set</span>
    <a class="floatingBoxLink smallText" href="#" onclick="reviewEditor.summon(this, 12074927, 'started_at', {value: null}); return false;">[edit]</a>
</div></td><td class="field date_read"><label>date read</label><div class="value">    <span class="greyText">not set</span>
    <a class="floatingBoxLink smallText" href="#" onclick="reviewEditor.summon(this, 12074927, 'read_at', {value: null}); return false;">[edit]</a>
</div></td><td class="field date_added" style="display: none"><label>date added</label><div class="value">  <span title="January 21, 2012">
    Jan 21, 2012
  </span>
</div></td><td class="field date_purchased" style="display: none"><label>date purchased</label><div class="value">    <a class="smallText" href="#" id="add_for_date_purchased" onclick="new Ajax.Request('/review/update/12074927?format=json', {asynchronous:true, evalScripts:true, onFailure:function(request){Element.hide('loading_anim_206609');$('add_for_date_purchased').innerHTML = '<span class=&quot;error&quot;>ERROR</span>try again';$('add_for_date_purchased').show();}, onLoading:function(request){;Element.show('loading_anim_206609');Element.hide('add_for_date_purchased')}, onSuccess:function(request){Element.hide('loading_anim_206609');Element.show('add_for_date_purchased');var json = eval('(' + request.responseText + ')');$('review_265364012').replace(json.html);if (typeof(toggleFieldsToMatchHeader) == 'function') {toggleFieldsToMatchHeader();}}, parameters:'owned_book[book_id]=12074927&amp;partial=bookalike&amp;view=table' + '&amp;authenticity_token=' + encodeURIComponent('J5JjYi/D31hPm9w3u8hM35umQTh8bK3md4dVzpi4eKQ=')}); return false;">(add)</a><img alt="Loading-trans" class="loading" id="loading_anim_206609" src="http://www.goodreads.com/assets/loading-trans-3e04cd6ed6ad31063972e688820d7866.gif" style="display:none">
</div></td><td class="field owned" style="display: none"><label>owned</label><div class="value"></div></td><td class="field purchase_location" style="display: none"><label>purchase location</label><div class="value">    <a class="smallText" href="#" id="add_for_purchase_location" onclick="new Ajax.Request('/review/update/12074927?format=json', {asynchronous:true, evalScripts:true, onFailure:function(request){Element.hide('loading_anim_953979');$('add_for_purchase_location').innerHTML = '<span class=&quot;error&quot;>ERROR</span>try again';$('add_for_purchase_location').show();}, onLoading:function(request){;Element.show('loading_anim_953979');Element.hide('add_for_purchase_location')}, onSuccess:function(request){Element.hide('loading_anim_953979');Element.show('add_for_purchase_location');var json = eval('(' + request.responseText + ')');$('review_265364012').replace(json.html);if (typeof(toggleFieldsToMatchHeader) == 'function') {toggleFieldsToMatchHeader();}}, parameters:'owned_book[book_id]=12074927&amp;partial=bookalike&amp;view=table' + '&amp;authenticity_token=' + encodeURIComponent('J5JjYi/D31hPm9w3u8hM35umQTh8bK3md4dVzpi4eKQ=')}); return false;">(add)</a><img alt="Loading-trans" class="loading" id="loading_anim_953979" src="http://www.goodreads.com/assets/loading-trans-3e04cd6ed6ad31063972e688820d7866.gif" style="display:none">
</div></td><td class="field condition" style="display: none"><label>condition</label><div class="value">    <a class="smallText" href="#" id="add_for_condition" onclick="new Ajax.Request('/review/update/12074927?format=json', {asynchronous:true, evalScripts:true, onFailure:function(request){Element.hide('loading_anim_990684');$('add_for_condition').innerHTML = '<span class=&quot;error&quot;>ERROR</span>try again';$('add_for_condition').show();}, onLoading:function(request){;Element.show('loading_anim_990684');Element.hide('add_for_condition')}, onSuccess:function(request){Element.hide('loading_anim_990684');Element.show('add_for_condition');var json = eval('(' + request.responseText + ')');$('review_265364012').replace(json.html);if (typeof(toggleFieldsToMatchHeader) == 'function') {toggleFieldsToMatchHeader();}}, parameters:'owned_book[book_id]=12074927&amp;partial=bookalike&amp;view=table' + '&amp;authenticity_token=' + encodeURIComponent('J5JjYi/D31hPm9w3u8hM35umQTh8bK3md4dVzpi4eKQ=')}); return false;">(add)</a><img alt="Loading-trans" class="loading" id="loading_anim_990684" src="http://www.goodreads.com/assets/loading-trans-3e04cd6ed6ad31063972e688820d7866.gif" style="display:none">
</div></td><td class="field format"><label>format</label><div class="value"></div></td><td class="field actions"><label>actions</label><div class="value">    <div class="actionsWrapper greyText smallText">
      <div class="editLinkWrapper"><a class="actionLinkLite editLink" href="#" id="loading_link_818479" onclick="new Ajax.Request('/review/edit/12074927', {asynchronous:true, evalScripts:true, onFailure:function(request){Element.hide('loading_anim_818479');$('loading_link_818479').innerHTML = '<span class=&quot;error&quot;>ERROR</span>try again';$('loading_link_818479').show();}, onLoading:function(request){;Element.show('loading_anim_818479');Element.hide('loading_link_818479')}, onSuccess:function(request){Element.hide('loading_anim_818479');Element.show('loading_link_818479');}, parameters:'authenticity_token=' + encodeURIComponent('J5JjYi/D31hPm9w3u8hM35umQTh8bK3md4dVzpi4eKQ=')}); return false;">edit</a><img alt="Loading-trans" class="loading" id="loading_anim_818479" src="http://www.goodreads.com/assets/loading-trans-3e04cd6ed6ad31063972e688820d7866.gif" style="display:none"></div>
      <div class="viewLinkWrapper"><a href="/review/show/265364012" class="actionLinkLite viewLink nobreak">view »</a></div>
      <a href="/review/destroy/12074927?return_url=http%3A%2F%2Fwww.goodreads.com%2Freview%2Flist%2F4111865%3Fshelf%3Dto-read" class="actionLinkLite smallText deleteLink" data-confirm="Are you sure you want to remove The Fractal Prince from your books? This will permanently remove this book from your shelves, including any review, rating, tags, or notes you have added. To change the shelf this book appears on please edit the shelves." data-method="post" rel="nofollow">        <img alt="Remove from my books" src="http://www.goodreads.com/assets/layout/delete.gif" title="Remove from my books">
        <span class="label">remove book</span>
</a>    </div>
</div></td>
</tr>

score 6 · Accepted Answer

该代码中至少有3个问题：

你不能那样锁链getElementsByClassName。该函数对DOM 元素进行操作，但返回一个对象。
for (var book in books)将循环未考虑的对象属性，并使此代码崩溃。 books是一个对象，而不是一个数组。
book.style.backgroundColor不是函数，也不是如何设置样式。
如今，getElementsByClassName很少有这种事情的最佳方法；使用querySelectorAll更多：灵活性/功率/精度。

解决所有问题，这里的代码应该可以工作——假设页面结构确实与问题中的代码结构相匹配。如果没有，请发布相关的 HTML 片段和/或指向确切页面的链接。

// ==UserScript==
// @name        Unpublished Lowlighter
// @description Makes the background of books not yet published on the Goodreads to-read shelf grey.
// @include     http://www.goodreads.com/*
// ==/UserScript==

function dateColor() {
    var books = document.querySelectorAll (
        ".bookalike.review .field.date_pub .value"
    );
    var today = new Date(); // More efficient, outside the loop.

    for (var J = books.length - 1;  J >= 0;  --J) {
        var book        = books[J];
        var dateString  = book.textContent;
        var date        = new Date(dateString);
        if (date > today) {
            book.parentNode.parentNode.style.setProperty ("background", "Lightgrey");
        }
    }
}

dateColor();

score 4 · Accepted Answer

还有一个问题（除了试图调用getElementsByClassNameNodeList 之外）for (var book in books)不会做你想做的事。in没有foreach像你期望的那样做；它从目标对象获取所有属性。由于 Javascript 对象的工作方式，对于数组，这将是数组索引；对于 NodeList，它是 NodeList 的属性（将是数组索引，加上字符串“length”和字符串“item”），这对您的循环没有用处。

你需要类似的东西

for (var i = 0; i < books.length; ++i) {
    var book = books[i];
    ...
}

score 3 · Accepted Answer

这不起作用：

book
    .getElementsByClassName('field date_pub')
    .getElementsByClassName('value')

getElementsByClassName返回适当元素的类数组对象（给定类可以有多个）。您将不得不遍历每一个并在每一个上执行getElementsByClassName。getElementsByClassName默认情况下不合并嵌套。

score 2 · Accepted Answer

您只能在单个 Element 对象上使用 getElementsByClassName，而不能像 getElementsByClassName 返回的那样使用 NodeList 或 HTMLCollection。也就是说，问题可能出在您的链接调用中，您在其中再次调用该函数本身。

score 2 · Accepted Answer

问题是您正在从getElementsByClassName.

假设您只是在寻找具有类名的第一个元素，这应该有效：

var dateString = book
                    .getElementsByClassName('field date_pub')[0]
                    .getElementsByClassName('value')[0]
                    .textContent;

javascript - getElementsByClassName 不是 Firefox 中的函数

5 回答 5

Related

Reference