⭐ 欢迎来到虫虫下载站！ | 📦 资源下载 📁 资源专辑 ℹ️ 关于我们
⭐ 虫虫下载站
📤 上传资源

📄 tutorial2_page7.html

📁 javascript从入门到精通； javascript从入门到精通
💻 HTML
字号:
🔍 
<html>

<head>
<meta HTTP-EQUIV="Content-Type" CONTENT="text/html; charset=gb_2312-80">
<meta NAME="GENERATOR" CONTENT="Microsoft FrontPage 3.0">
<title>Webmonkey: javascript: Thau's JavaScript Tutorial: Day 1</title>
<meta NAME="keywords"
CONTENT="javascript, hotwired, webmonkey, javascript, javascript tutorial, thau, dave thau, developer resource, developer, development, web

development, design, code, geek, warez, free, new, latest, news, tools,

info, tutorials, how-to, builder, web builder, pag">
<meta NAME="description"
CONTENT="Thau's JavaScript Tutorial: Day 1: Not only does Thau give the JavaScript skinny, but he'll have you writing your first script by the end of the day.">
<meta NAME="Template" CONTENT="E:\LIZEJUN\OFFICE\html.dot">
</head>

<body TEXT="#000000" LINK="#0000ff" VLINK="#800080" BGCOLOR="#ffffff">

<table CELLSPACING="0" BORDER="0" CELLPADDING="3" WIDTH="540">
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE"><font FACE="宋体" LANG="ZH-CN" SIZE="4" COLOR="#ff0000"></font><b><font
    FACE="System,黑体" LANG="ZH-CN" COLOR="#ff0000">第</font><font FACE="宋体"
    LANG="ZH-CN" COLOR="#ff0000">7</font><font FACE="System,黑体" LANG="ZH-CN"
    COLOR="#ff0000">页</font><font FACE="宋体" LANG="ZH-CN" COLOR="#ff0000">: </font><font
    FACE="System,黑体" LANG="ZH-CN" COLOR="#ff0000">一个简单的</font><font
    FACE="宋体" LANG="ZH-CN" COLOR="#ff0000"> if-then </font><font FACE="System,黑体"
    LANG="ZH-CN" COLOR="#ff0000">语句的例子</font></b><font FACE="System,黑体"
    LANG="ZH-CN"><br>
<!-- BYLINE (commented out for PageX) --><!--    <font size=1 color="#000000" face="arial, helvetica, sans-serif">by <a href="mailto:thau@wired.com" title="Send mail to Thau!">Thau!</a></font>-->    </font><font FACE="宋体" LANG="ZH-CN"><br>
<!-- BYLINE -->    </font><font FACE="System,黑体" LANG="ZH-CN" SIZE="2">作者：</font><a
    HREF="mailto:thau@wired.com"><font FACE="宋体" LANG="ZH-CN" SIZE="2">Thau!</font></a><font
    FACE="宋体" LANG="ZH-CN"> <!-- SEE ALSO LINKS --></font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="TOP" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN"></font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN"></font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">如果你在即时对话框中键入</font><tt>yes</tt><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">，你将在看到本页<br>
    其他部分前收到一个亲切的问候。若敲入别的则<br>
    没有。<p>这里是该语句的核心：</font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="TOP" BGCOLOR="#ffffff"><pre>

var monkey_love = prompt(&quot;Do you love the monkey?&quot;,&quot;Type yes or no&quot;);

if (monkey_love == &quot;yes&quot;)

{

  alert(&quot;Welcome! I'm so glad you came! Please, read on!&quot;);

}
</pre>
    </td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN"></font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">第一行你见过。它唤起一个对话框并将用户的反馈调入<br>
    变量</font><tt>monkey_love</tt><font FACE="System,黑体" LANG="ZH-CN" SIZE="2">中。但第二行就有些不同：它有个条<br>
    件，即如果变量</font><tt>monkey_love</tt><font FACE="System,黑体" LANG="ZH-CN"
    SIZE="2">等于值</font><font FACE="宋体" LANG="ZH-CN" SIZE="2">&quot;yes&quot; </font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">，则运行花<br>
    括号中的语句。若它等于其他值，则不运行。<p>注意该条件中的两个等于标记，这是人们容易搞混的<br>
    地方之一。如果你只用一个标记，实际上是告诉<br>
    </font><font FACE="宋体" LANG="ZH-CN" SIZE="2">JavaScript</font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">测试是否</font><tt>monkey_love<font
    FACE="System,黑体" LANG="ZH-CN">等于</font></tt><font FACE="宋体" LANG="ZH-CN"
    SIZE="2"> &quot;yes&quot;</font><font FACE="System,黑体" LANG="ZH-CN" SIZE="2">。<br>
    幸运的是，多数浏览器在你运行这些语句时会识别<br>
    这些错误并警告你。但最好现在开始就注意别犯这<br>
    种错误</p>
    <p>其他重要的条件是：</font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="TOP" BGCOLOR="#ffffff"><pre>
(variable_1 &gt; variable_2)  is true if variable_1 is greater than variable_2

(variable_1 &lt; variable_2)  is true if variable_1 is less than variable_2

(variable_2 &lt;= variable_2)  is true if variable_1 is less than or equal to variable_2

(variable_1 != variable_2)  is true if variable_1 does <b>not</b> equal variable_2
</pre>
    </td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN"></font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">有两个方法可使你的条件更合理：<p>在运行花括号中的语句前如果你想要两件事为“是”，<br>
    可这样做：</font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="TOP" BGCOLOR="#ffffff"><pre>

if ((variable_1 &gt; 18) &amp;&amp; (variable_1 &lt; 21)) 

{ 

  document.writeln(&quot;variable_1 can vote, but can't drink.&quot;);

}
</pre>
    </td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN"></font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">注意这里的两个“</font><font
    FACE="宋体" LANG="ZH-CN" SIZE="2">&amp;&amp;</font><font FACE="System,黑体"
    LANG="ZH-CN" SIZE="2">”在</font><font FACE="宋体" LANG="ZH-CN" SIZE="2">JavaScript</font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">中这是“与”的<br>
    意思。也注意整个子句有两个部分，</font><font FACE="宋体" LANG="ZH-CN"
    SIZE="2">&amp;&amp;</font><font FACE="System,黑体" LANG="ZH-CN" SIZE="2">须在圆括号中。<p>若想两件事之一为真，这样做：</font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="TOP" BGCOLOR="#ffffff"><pre>

if ((variable_1 == &quot;bananas&quot;) || (variable_1 == &quot;JavaScript&quot;)) 

{ 

  document.writeln(&quot;The monkey is happy because it has &quot; +  variable_1);

}
</pre>
    </td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN"></font><font
    FACE="System,黑体" LANG="ZH-CN" SIZE="2">回到</font><a HREF="tutorial2_page8.html"><font
    FACE="宋体" LANG="ZH-CN" SIZE="2">if-then </font><font FACE="System,黑体" LANG="ZH-CN"
    SIZE="2">练习中来</font><font FACE="宋体" LANG="ZH-CN" SIZE="2">!</a> </font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="TOP" BGCOLOR="#ffffff"><font FACE="System,黑体" LANG="ZH-CN">第</font><font
    FACE="宋体" LANG="ZH-CN">1</font><font FACE="System,黑体" LANG="ZH-CN">页：<a
    HREF="tutorial2.html">第二天课程简介</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">2</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: </font><font FACE="System,黑体" LANG="ZH-CN"><a
    HREF="tutorial2_page2.html">变量介绍</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">3</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">:</font><font FACE="System,黑体" LANG="ZH-CN"><a
    HREF="tutorial2_page3.html">首个变量例子的程序主体</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">4</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: </font><font FACE="System,黑体" LANG="ZH-CN"><a
    HREF="tutorial2_page4.html">字符串的魔力</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">5</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: </font><font FACE="System,黑体" LANG="ZH-CN"><a
    HREF="tutorial2_page5.html">变量练习</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">6</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: <a HREF="tutorial2_page6.html">if-then </font><font
    FACE="System,黑体" LANG="ZH-CN">子句</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">7</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: <a HREF="tutorial2_page7.html">if-then </font><font
    FACE="System,黑体" LANG="ZH-CN">语句的例子</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">8</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: <a HREF="tutorial2_page8.html">if-then </font><font
    FACE="System,黑体" LANG="ZH-CN">练习</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">9</font><font FACE="System,黑体" LANG="ZH-CN">页</font><font
    FACE="宋体" LANG="ZH-CN">: </font><font FACE="System,黑体" LANG="ZH-CN"><a
    HREF="tutorial2_page9.html">链结事件</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">10</font><font FACE="System,黑体"
    LANG="ZH-CN">页</font><font FACE="宋体" LANG="ZH-CN">: </font><font
    FACE="System,黑体" LANG="ZH-CN"><a HREF="tutorial2_page10.html">图片交换</a><br>
    第</font><font FACE="宋体" LANG="ZH-CN">11</font><font FACE="System,黑体"
    LANG="ZH-CN">页</font><font FACE="宋体" LANG="ZH-CN">: </font><a
    HREF="tutorial2_page11.html"><font FACE="System,黑体" LANG="ZH-CN">练习</font><font
    FACE="宋体" LANG="ZH-CN"> 2</a><br>
    </font><font FACE="System,黑体" LANG="ZH-CN">第</font><font FACE="宋体" LANG="ZH-CN">12</font><font
    FACE="System,黑体" LANG="ZH-CN">页</font><font FACE="宋体" LANG="ZH-CN">: </font><font
    FACE="System,黑体" LANG="ZH-CN"><a HREF="tutorial2_page12.html">复习</a><br>
    </font></td>
  </tr>
  <tr>
    <td WIDTH="68%" VALIGN="MIDDLE"></td>
  </tr>
</table>
<font FACE="System,黑体" LANG="ZH-CN">

<p>　</p>
</font>
</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 + -