📄 day2_4.html
字号:
<html>
<head>
<meta http-equiv="Content-Type" content="text/html; charset=gb2312-80">
<style type="text/css">
<!--
a:link { color: blue; text-decoration: none}
a:visited { color: purple; text-decoration: none}
a:hover { color: #CC0033; text-decoration: underline}
-->
</style>
<title>JavaScript教程</title>
</head>
<body topmargin="1" leftmargin="2">
<table border="0" width="591" cellspacing="0">
<tr>
<td bgcolor="#ffff99" width="451">JavaScript教程 - 第二课</td>
</tr>
<tr>
<td bgcolor="#FF6600" width="451"><a href="mailto:thau@wired.com">Thau</a></td>
</tr>
</table>
<div align="left">
<table border="0" width="630" cellspacing="0">
<tr>
<td width="458" valign="top" align="left"><strong><small><small><br>
</small></small><font face="宋体" size="3">第四页：字符串的魔力</font></strong>
<p><font face="宋体" size="3">如前一节所提，引号间的字符都称为字符串，无论单双引号。<br>
就如变量可为数字一样，它也可为字符串。因此可说：</font></p>
<p><font face="宋体" size="3">var nice_monkey = "The monkey smiles at you and
recites Shakespeare.";<br>
<br>
var bad_monkey = "The monkey scowls at you and burps.";<br>
<br>
</font></p>
<p><font face="宋体" size="3">申报变量时即给变量赋值，使它等于这些字符串，于是当你想<br>
写这些字符串时，你可写：</font></p>
<p><font face="宋体" size="3"><br>
document.writeln(nice_monkey);<br>
<br>
</font></p>
<p><font face="宋体" size="3">这里是可用字符串做事的例子。</font></p>
<p><font face="宋体" size="3">仔细看一看源码，你将常会发现一些新鲜，有趣的事。</font></p>
<p><font face="宋体" size="3">看以下新鲜之处:</font></p>
<p><font face="宋体" size="3"><br>
var monkey = prompt("What's the monkey's name?", "The monkey");<br>
<br>
</font></p>
<p><font face="宋体" size="3">这里我们称为用户反馈提示方式，当它被调用时，启动一个对<br>
话框请求用户输入信息。用户完成后敲OK返回信息。在上行中<br>
返回信息放入其变量中。 </font></p>
<p><font face="宋体" size="3">注意该提示方式有两个变量，且都是字符串。第一个在对话框<br>
输入区上面显示，本例中它是：“What's the monkey's <br>
name?”。本例中第二个参数"The monkey"，放置输入框的缺<br>
省值。如果你不想要缺省值，则在第二个参数加上引号，就象<br>
这样：</font></p>
<p><font face="宋体" size="3"><br>
var monkey = prompt("What's the monkey's name?", "");<br>
<br>
</font></p>
<p><font face="宋体" size="3">下一行是直接变量分配，就象此前我们看到的：</font></p>
<p><font face="宋体" size="3"><br>
var techy_monkey = monkey + demanding + tech;<br>
<br>
</font></p>
<p><font face="宋体"><font size="3">该行介绍了一个字符串操作器：累加标记。当两个字符串间出<br>
现累加标记时，则这两个变量出现在同一字符串中，这称为<br>
“<a href="javascript:if(confirm('http://www.pcwebopedia.com/concatenate.htm \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://www.pcwebopedia.com/concatenate.htm'" tppabs="http://www.pcwebopedia.com/concatenate.htm" target="_blank">连锁</a>”。于是上行创造了一个新的变量称为<tt>techy_monkey<br>
</font><font size="4">含有包含上述三个变量的字符串。换一句话说，其结果即是<br>
</font></tt><font size="3">"<tt>The monkey</tt>" + "<tt>demands, no,
insists upon receiving</tt>" + <br>
"<tt>a computer that won't crash, and a homemade browser!</tt>"</font></font></p>
<p><font face="宋体" size="3"><br>
var techy_monkey = monkey + demanding + tech;<br>
<br>
于是也可说：</font></p>
<p><font face="宋体" size="3"><br>
var techy_monkey = "The monkey demands, no, insists upon<br>
receiving a computer <br>
<br>
that won't crash, and a homemade browser!";<br>
<br>
</font></p>
<p><font face="宋体" size="3">下面一段显示更多的使用字符串的诀窍。其工作原理是相同<br>
的，我们只看三行：</font></p>
<p><font face="宋体" size="3"><br>
var italic_hippy = hippy_monkey.italics();<br>
<br>
var shouting_hippy= hippy_monkey.toUpperCase();<br>
<br>
var red_bold_tech = bold_tech.fontcolor('red');<br>
<br>
第一行是说：“使该字符串包含变量以斜体显示”，这实际上<br>
即是：</font></p>
<p><font face="宋体" size="3"><br>
var italic_hippy = "<i>" + hippy_monkey + "</i>";<br>
<br>
</font></p>
<p><font face="宋体" size="3">但看起来要好的多！今后在JavaScript写<tt>document.writeln<br>
(italic_hippy)</tt>时，你得到的是斜体显示的字符。</font></p>
<p><font face="宋体" size="3">下一行讲述的技巧是在HTML中实现不了的，它使得<tt>hippy_monkey</tt><br>
中所有字符以大写显示</font></p>
<p><font face="宋体" size="3">第三行显示改变字符串属性的例子。。所有的字符具有颜色，<br>
你可用<tt>string.fontcolor('new color');</tt>命令改变其颜色。也<br>
可这样作：</font></p>
<p><font face="宋体" size="3"><br>
var red_bold_tech = "<font color='red'>" + bold_tech +
"</font>";<br>
<br>
但它阅读起来不如这样容易： </font></p>
<p><font face="宋体" size="3">var red_bold_tech = bold_tech.fontcolor('red');<br>
<br>
本例中除本行外你还可看到其他的应用：</font></p>
<p><font face="宋体" size="3">document.writeln(bold_tech + "<br>");<br>
<br>
它除替代显示一字符串外，还连接两个字符串然后显示结果。<br>
也可写成两行，象这样：</font></p>
<p><font face="宋体" size="3">var broken_bold = bold_tech + "<br>";<br>
<br>
document.writeln(broken_bold);<br>
<br>
</font></p>
<p><font face="宋体" size="3">但这要创建另一个变量，并不必要的写另一行。</font></p>
<p><font face="宋体" size="3">现在我们已学习了所有的关于变量和字符串知识，<a
href="day2_5.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_5.html">请做一个练习</a></font></p>
<p align="left"><font face="宋体" size="3" color="#000000"><strong>JavaScript教程</strong></font><font
color="#FF0000" face="宋体" size="3"><br>
</font><font face="宋体" size="3"><font color="#FF0000">第一页</font>：<a
href="day2_4.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_4.html">第二天课程简介</a><br>
<font color="#FF0000">第二页</font>：<a href="day2_2.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_2.html">变量介绍</a><br>
<font color="#FF0000">第三页</font>：<a href="day2_3.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_3.html">首个变量例子的程序主体</a><br>
<font color="#FF0000">第四页</font>：字符串的魔力<br>
<font color="#FF0000">第五页</font>：<a href="day2_5.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_5.html">变量练习</a><br>
<font color="#FF0000">第六页</font>：<a href="day2_6.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_6.html">if-then子句</a><br>
<font color="#FF0000">第七页</font>：<a href="day2_7.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_7.html">if-then语句的例子</a><br>
<font color="#FF0000">第八页</font>：<a href="day2_8.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_8.html">if-then练习</a><br>
<font color="#FF0000">第九页</font>：<a href="day2_9.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_9.html">链结事件</a><br>
<font color="#FF0000">第十页</font>：<a href="day2_10.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_10.html">图片交换</a><br>
<font color="#FF0000">第十一页</font>：<a href="day2_11.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_11.html">练习2</a><br>
<font color="#FF0000">第十二页</font>：<a href="day2_12.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day2_12.html">复习</a></font></p>
<p align="left"><font face="宋体" size="3">[<a href="index.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/index.html">第1课</a>][第2课][<a
href="day3_1.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day3_1.html">第3课</a>][<a href="day4_1.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day4_1.html">第4课</a>][<a href="day5_1.html" tppabs="http://www.pchome.net/ch/tur/pstext/teacher/javascript/day5_1.html">第5课</a>]</font></p>
<hr align="left">
<p><font size="2">本文由<a href="javascript:if(confirm('http://chd.126.com/ \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://chd.126.com/'" tppabs="http://chd.126.com/" target="_blank">《</font><font
face="verdana, arial, geneva, sans-serif" size="2">CHD</font><font size="2">的网络教室》</a>根据<a
href="javascript:if(confirm('http://www.webmonkey.com.cn/ \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://www.webmonkey.com.cn/'" tppabs="http://www.webmonkey.com.cn/" target="_blank">《网猴》</a>相关文章改编，版权归<a
href="javascript:if(confirm('http://www.webmonkey.com.cn/ \n\nThis file was not retrieved by Teleport Pro, because it is addressed on a domain or path outside the boundaries set for its Starting Address. \n\nDo you want to open it from the server?'))window.location='http://www.webmonkey.com.cn/'" tppabs="http://www.webmonkey.com.cn/" target="_blank">《网猴》</a>所有</font></td>
</tr>
</table>
</div>
</body>
</html>
⌨️ 快捷键说明
复制代码
Ctrl + C
搜索代码
Ctrl + F
全屏模式
F11
切换主题
Ctrl + Shift + D
显示快捷键
?
增大字号
Ctrl + =
减小字号
Ctrl + -