所以我在JavaScript / Jquery类中，对于我目前的作业，我需要在文章的第4段之后插入一个回到顶部的链接。我觉得这是一种选择特定段落的方法：
$("p").eq(1).css("background-color", "yellow");
我需要弄清楚如何在现有的Jquery中使用它：
// Add "back to top" links.
$('<a href="#top">back to top</a>').insertAfter('article.chapter p');
$('<a id="top"></a>').prependTo('body');
我的想法是这样做：
// Add "back to top" links.
$('<a href="#top">back to top</a>').insertAfter("article.chapter p").eq(3).
$('<a id="top"></a>').prependTo('body');
这不起作用，我今天早些时候才刚刚了解了这项技术。做这个的最好方式是什么。
这是HTML：
<!DOCTYPE html>
<!--Lisa Hergert's Assignment 6-->
<html lang="en">
<head>
<meta charset="utf-8">
<title>Flatland</title>
<link rel="stylesheet" href="05.css" type="text/css" />
<script src="jquery.js"></script>
<script src="complete.js"></script>
<script src="prep.js"></script>
</head>
<body>
<main id="container">
<h1 id="f-title">Flatland: A Romance of Many Dimensions</h1>
<p id="f-author">by Edwin A. Abbott</p>
<h2>Part 1, Section 3</h2>
<h3 id="f-subtitle">Concerning the Inhabitants of Flatland</h3>
<p id="excerpt">an excerpt</p>
<article class="chapter">
<p class="square">Our Professional Men and Gentlemen are Squares (to which class I myself belong) and Five-Sided Figures or <a href="http://en.wikipedia.org/wiki/Pentagon">Pentagons</a>.</p>
<p class="nobility hexagon">Next above these come the Nobility, of whom there are several degrees, beginning at Six-Sided Figures, or <a href="http://en.wikipedia.org/wiki/Hexagon">Hexagons</a>, and from thence rising in the number of their sides till they receive the honourable title of <a href="http://en.wikipedia.org/wiki/Polygon">Polygonal</a>, or many-Sided. Finally when the number of the sides becomes so numerous, and the sides themselves so small, that the figure cannot be distinguished from a <a href="http://en.wikipedia.org/wiki/Circle">circle</a>, he is included in the Circular or Priestly order; and this is the highest class of all.</p>
<p><span class="pull-quote">It is a Law of Nature <span class="drop">with us</span> that a male child shall have <strong>one more side</strong> than his father</span>, so that each generation shall rise (as a rule) one step in the scale of development and nobility. Thus the son of a Square is a Pentagon; the son of a Pentagon, a Hexagon; and so on.</p>
<p>But this rule applies not always to the Tradesman, and still less often to the Soldiers, and to the Workmen; who indeed can hardly be said to deserve the name of human Figures, since they have not all their sides equal. With them therefore the Law of Nature does not hold; and the son of an Isosceles (i.e. a Triangle with two sides equal) remains Isosceles still. Nevertheless, all hope is not such out, even from the Isosceles, that his posterity may ultimately rise above his degraded condition.…</p>
<p>Rarely—in proportion to the vast numbers of Isosceles births—is a genuine and certifiable Equal-Sided Triangle produced from Isosceles parents. <span class="footnote">"What need of a certificate?" a Spaceland critic may ask: "Is not the procreation of a Square Son a certificate from Nature herself, proving the Equal-sidedness of the Father?" I reply that no Lady of any position will marry an uncertified Triangle. Square offspring has sometimes resulted from a slightly Irregular Triangle; but in almost every such case the Irregularity of the first generation is visited on the third; which either fails to attain the Pentagonal rank, or relapses to the Triangular.</span> Such a birth requires, as its antecedents, not only a series of carefully arranged intermarriages, but also a long-continued exercise of frugality and self-control on the part of the would-be ancestors of the coming Equilateral, and a patient, systematic, and continuous development of the Isosceles intellect through many generations.</p>
<p><span class="pull-quote">The birth of a True Equilateral Triangle from Isosceles parents is the subject of rejoicing in our country <span class="drop">for many furlongs round</span>.</span> After a strict examination conducted by the Sanitary and Social Board, the infant, if certified as Regular, is with solemn ceremonial admitted into the class of Equilaterals. He is then immediately taken from his proud yet sorrowing parents and adopted by some childless Equilateral. <span class="footnote">The Equilateral is bound by oath never to permit the child henceforth to enter his former home or so much as to look upon his relations again, for fear lest the freshly developed organism may, by force of unconscious imitation, fall back again into his hereditary level.</span></p>
<p>How admirable is the Law of Compensation! <span class="footnote">And how perfect a proof of the natural fitness and, I may almost say, the divine origin of the aristocratic constitution of the States of Flatland!</span> By a judicious use of this Law of Nature, the Polygons and Circles are almost always able to stifle sedition in its very cradle, taking advantage of the irrepressible and boundless hopefulness of the human mind.…</p>
<p>Then the wretched rabble of the Isosceles, planless and leaderless, are ether transfixed without resistance by the small body of their brethren whom the Chief Circle keeps in pay for emergencies of this kind; or else more often, by means of jealousies and suspicious skillfully fomented among them by the Circular party, they are stirred to mutual warfare, and perish by one another's angles. No less than one hundred and twenty rebellions are recorded in our annals, besides minor outbreaks numbered at two hundred and thirty-five; and they have all ended thus.</p>
</article>
<footer id="footer">
<p>Read the <a href="http://web.archive.org/web/20050208012252/http://www.ibiblio.org/eldritch/eaa/FL.HTM">complete text of <i>Flatland</i></a>.</p>
</footer>
</main>
</body>
</html>
我还需要在点击时加粗作者姓名，然后再次点击它时删除该粗体。
这就是我所拥有的，只有一半有效：
// Clicking on authors name makes it bold
$("#f-author").one ("click", function() {
$(this).wrap("<b id = 'bold'></b>");
});
$("#bold").one ("dblclick", function() {
$(this).remove();
});
谢谢。
有一件事让我感到困惑，我需要添加班级＆＃34;居民＆＃34;不使用addClass（）调用到章节中的所有段落。我已经看了几个选项，一个效果最好的选项，但制作凌乱的html是用一个新的段落元素包装所有段落。我不知道还有什么可以用于此，因为有些段落已经有了一个类，需要坚持下去。
答案 0 :(得分：1)
您需要使用insertAfter("article.chapter p:eq(3)")，以便选择第四个p。注意:eq(3)中的伪类insertAfter，它只会从段落列表中选择第四段。
此外，如果您想要每个四段后面的链接，那么您需要遍历段落并动态设置:eq()。
var i = 4;
var elem = $('article.chapter p');
$('<a id="top"></a>').prependTo('body');
while(i<=elem.length){
$('<a href="#top">back to top</a>').insertAfter("article.chapter p:eq("+(i-1)+")");
i+=4;
}<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<article class="chapter">
<p class="square">Our Professional Men and Gentlemen are Squares (to which class I myself belong) and Five-Sided Figures or <a href="http://en.wikipedia.org/wiki/Pentagon">Pentagons</a>.</p>
<p class="nobility hexagon">Next above these come the Nobility, of whom there are several degrees, beginning at Six-Sided Figures, or <a href="http://en.wikipedia.org/wiki/Hexagon">Hexagons</a>, and from thence rising in the number of their sides till they receive the honourable title of <a href="http://en.wikipedia.org/wiki/Polygon">Polygonal</a>, or many-Sided. Finally when the number of the sides becomes so numerous, and the sides themselves so small, that the figure cannot be distinguished from a <a href="http://en.wikipedia.org/wiki/Circle">circle</a>, he is included in the Circular or Priestly order; and this is the highest class of all.</p>
<p><span class="pull-quote">It is a Law of Nature <span class="drop">with us</span> that a male child shall have <strong>one more side</strong> than his father</span>, so that each generation shall rise (as a rule) one step in the scale of development and nobility. Thus the son of a Square is a Pentagon; the son of a Pentagon, a Hexagon; and so on.</p>
<p>But this rule applies not always to the Tradesman, and still less often to the Soldiers, and to the Workmen; who indeed can hardly be said to deserve the name of human Figures, since they have not all their sides equal. With them therefore the Law of Nature does not hold; and the son of an Isosceles (i.e. a Triangle with two sides equal) remains Isosceles still. Nevertheless, all hope is not such out, even from the Isosceles, that his posterity may ultimately rise above his degraded condition.…</p>
<p>Rarely—in proportion to the vast numbers of Isosceles births—is a genuine and certifiable Equal-Sided Triangle produced from Isosceles parents. <span class="footnote">"What need of a certificate?" a Spaceland critic may ask: "Is not the procreation of a Square Son a certificate from Nature herself, proving the Equal-sidedness of the Father?" I reply that no Lady of any position will marry an uncertified Triangle. Square offspring has sometimes resulted from a slightly Irregular Triangle; but in almost every such case the Irregularity of the first generation is visited on the third; which either fails to attain the Pentagonal rank, or relapses to the Triangular.</span> Such a birth requires, as its antecedents, not only a series of carefully arranged intermarriages, but also a long-continued exercise of frugality and self-control on the part of the would-be ancestors of the coming Equilateral, and a patient, systematic, and continuous development of the Isosceles intellect through many generations.</p>
<p><span class="pull-quote">The birth of a True Equilateral Triangle from Isosceles parents is the subject of rejoicing in our country <span class="drop">for many furlongs round</span>.</span> After a strict examination conducted by the Sanitary and Social Board, the infant, if certified as Regular, is with solemn ceremonial admitted into the class of Equilaterals. He is then immediately taken from his proud yet sorrowing parents and adopted by some childless Equilateral. <span class="footnote">The Equilateral is bound by oath never to permit the child henceforth to enter his former home or so much as to look upon his relations again, for fear lest the freshly developed organism may, by force of unconscious imitation, fall back again into his hereditary level.</span></p>
<p>How admirable is the Law of Compensation! <span class="footnote">And how perfect a proof of the natural fitness and, I may almost say, the divine origin of the aristocratic constitution of the States of Flatland!</span> By a judicious use of this Law of Nature, the Polygons and Circles are almost always able to stifle sedition in its very cradle, taking advantage of the irrepressible and boundless hopefulness of the human mind.…</p>
<p>Then the wretched rabble of the Isosceles, planless and leaderless, are ether transfixed without resistance by the small body of their brethren whom the Chief Circle keeps in pay for emergencies of this kind; or else more often, by means of jealousies and suspicious skillfully fomented among them by the Circular party, they are stirred to mutual warfare, and perish by one another's angles. No less than one hundred and twenty rebellions are recorded in our annals, besides minor outbreaks numbered at two hundred and thirty-five; and they have all ended thus.</p>
<p> that a male child shall have <strong>one more side</strong> than his father so that each generation shall rise (as a rule) one step in the scale of development and nobility. Thus the son of a Square is a Pentagon; the son of a Pentagon, a Hexagon; and so on.</p>
<p>But this rule applies not always to the Tradesman, and still less often to the Soldiers, and to the Workmen; who indeed can hardly be said to deserve the name of human Figures, since they have not all their sides equal. With them therefore the Law of Nature does not hold; and the son of an Isosceles (i.e. a Triangle with two sides equal) remains Isosceles still. Nevertheless, all hope is not such out, even from the Isosceles, that his posterity may ultimately rise above his degraded condition.…</p>
<p>Rarely—in proportion to the vast numbers of Isosceles births—is a genuine and certifiable Equal-Sided Triangle produced from Isosceles parents. <span class="footnote">"What need of a certificate?" a Spaceland critic may ask: "Is not the procreation of a Square Son a certificate from Nature herself, proving the Equal-sidedness of the Father?" I reply that no Lady of any position will marry an uncertified Triangle. Square offspring has sometimes resulted from a slightly Irregular Triangle; but in almost every such case the Irregularity of the first generation is visited on the third; which either fails to attain the Pentagonal rank, or relapses to the Triangular.</span> Such a birth requires, as its antecedents, not only a series of carefully arranged intermarriages, but also a long-continued exercise of frugality and self-control on the part of the would-be ancestors of the coming Equilateral, and a patient, systematic, and continuous development of the Isosceles intellect through many generations.</p>
<p><span class="pull-quote">The birth of a True Equilateral Triangle from Isosceles parents is the subject of rejoicing in our country <span class="drop">for many furlongs round</span>.</span> After a strict examination conducted by the Sanitary and Social Board, the infant, if certified as Regular, is with solemn ceremonial admitted into the class of Equilaterals. He is then immediately taken from his proud yet sorrowing parents and adopted by some childless Equilateral. <span class="footnote">The Equilateral is bound by oath never to permit the child henceforth to enter his former home or so much as to look upon his relations again, for fear lest the freshly developed organism may, by force of unconscious imitation, fall back again into his hereditary level.</span></p>
<p> that a male child shall have <strong>one more side</strong> than his father so that each generation shall rise (as a rule) one step in the scale of development and nobility. Thus the son of a Square is a Pentagon; the son of a Pentagon, a Hexagon; and so on.</p>
<p>But this rule applies not always to the Tradesman, and still less often to the Soldiers, and to the Workmen; who indeed can hardly be said to deserve the name of human Figures, since they have not all their sides equal. With them therefore the Law of Nature does not hold; and the son of an Isosceles (i.e. a Triangle with two sides equal) remains Isosceles still. Nevertheless, all hope is not such out, even from the Isosceles, that his posterity may ultimately rise above his degraded condition.…</p>
<p>Rarely—in proportion to the vast numbers of Isosceles births—is a genuine and certifiable Equal-Sided Triangle produced from Isosceles parents. <span class="footnote">"What need of a certificate?" a Spaceland critic may ask: "Is not the procreation of a Square Son a certificate from Nature herself, proving the Equal-sidedness of the Father?" I reply that no Lady of any position will marry an uncertified Triangle. Square offspring has sometimes resulted from a slightly Irregular Triangle; but in almost every such case the Irregularity of the first generation is visited on the third; which either fails to attain the Pentagonal rank, or relapses to the Triangular.</span> Such a birth requires, as its antecedents, not only a series of carefully arranged intermarriages, but also a long-continued exercise of frugality and self-control on the part of the would-be ancestors of the coming Equilateral, and a patient, systematic, and continuous development of the Isosceles intellect through many generations.</p>
<p><span class="pull-quote">The birth of a True Equilateral Triangle from Isosceles parents is the subject of rejoicing in our country <span class="drop">for many furlongs round</span>.</span> After a strict examination conducted by the Sanitary and Social Board, the infant, if certified as Regular, is with solemn ceremonial admitted into the class of Equilaterals. He is then immediately taken from his proud yet sorrowing parents and adopted by some childless Equilateral. <span class="footnote">The Equilateral is bound by oath never to permit the child henceforth to enter his former home or so much as to look upon his relations again, for fear lest the freshly developed organism may, by force of unconscious imitation, fall back again into his hereditary level.</span></p>
<p> that a male child shall have <strong>one more side</strong> than his father so that each generation shall rise (as a rule) one step in the scale of development and nobility. Thus the son of a Square is a Pentagon; the son of a Pentagon, a Hexagon; and so on.</p>
<p>But this rule applies not always to the Tradesman, and still less often to the Soldiers, and to the Workmen; who indeed can hardly be said to deserve the name of human Figures, since they have not all their sides equal. With them therefore the Law of Nature does not hold; and the son of an Isosceles (i.e. a Triangle with two sides equal) remains Isosceles still. Nevertheless, all hope is not such out, even from the Isosceles, that his posterity may ultimately rise above his degraded condition.…</p>
<p>Rarely—in proportion to the vast numbers of Isosceles births—is a genuine and certifiable Equal-Sided Triangle produced from Isosceles parents. <span class="footnote">"What need of a certificate?" a Spaceland critic may ask: "Is not the procreation of a Square Son a certificate from Nature herself, proving the Equal-sidedness of the Father?" I reply that no Lady of any position will marry an uncertified Triangle. Square offspring has sometimes resulted from a slightly Irregular Triangle; but in almost every such case the Irregularity of the first generation is visited on the third; which either fails to attain the Pentagonal rank, or relapses to the Triangular.</span> Such a birth requires, as its antecedents, not only a series of carefully arranged intermarriages, but also a long-continued exercise of frugality and self-control on the part of the would-be ancestors of the coming Equilateral, and a patient, systematic, and continuous development of the Isosceles intellect through many generations.</p>
<p><span class="pull-quote">The birth of a True Equilateral Triangle from Isosceles parents is the subject of rejoicing in our country <span class="drop">for many furlongs round</span>.</span> After a strict examination conducted by the Sanitary and Social Board, the infant, if certified as Regular, is with solemn ceremonial admitted into the class of Equilaterals. He is then immediately taken from his proud yet sorrowing parents and adopted by some childless Equilateral. <span class="footnote">The Equilateral is bound by oath never to permit the child henceforth to enter his former home or so much as to look upon his relations again, for fear lest the freshly developed organism may, by force of unconscious imitation, fall back again into his hereditary level.</span></p>
</article>
<footer id="footer">
<p>Read the <a href="http://web.archive.org/web/20050208012252/http://www.ibiblio.org/eldritch/eaa/FL.HTM">complete text of <i>Flatland</i></a>.</p>
</footer>