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<title>JavaScrip高级教程</title>
<strong>第五页：<font size="3">好的编程实践</font></strong>
<p>编好程序的关键是程序是写给人的，不是写给计算机的。如<br>
果你能明白其他人或许会阅读你的JavaScript，你就会写更<br>
清晰的代码。代码越清晰，你就越不容易犯错误。机灵的代<br>
码是可爱的，但就是这种机灵的代码会产生错误。最好的经<br>
验法则是KISS，即Keep It Simple,Sweetie（保持简单，可爱）。</p>
<p>另一个有帮助的技术是在写代码之前作注释。这迫使你在动<br>
手之前先想好。一旦写好了注释，你就可以在其下面写代码。<br>
下面是一个用这种方法写函数的例子：</p>
<p><strong>第一步：写注释</strong></p>
<blockquote>
<pre>//function beSassy()
// beSassy asks for a user's name, chooses a random
// insult and returns an alert box with the user's name and the
// insult.
function beSassy()
{
// first write a list of insults
//
// next get the user's name
//
// then choose a random insult
//
// finally, return the personalized sass
//
}</pre>
</blockquote>
<p><strong>第二步：填充代码</strong></p>
<blockquote>
<pre>//function beSassy()
// beSassy asks for a user's name, chooses a random
// insult and returns an alert box with the user's name and the
// insult.
function beSassy()
{
// first write a list of insults
//
var the_insult_list = new Array;
the_insult_list[0] = "your shoe lace is untied";
the_insult_list[1] = "your mama!";
the_insult_list[2] = "it's hard to be insulting";
// next get the user's name
//
var the_name = prompt("What's your name?", "");
// then choose a random insult
//
var the_number = Math.random() * 5;
var insult_number = parseInt(the_number);
var the_insult = the_insult_list[insult_number];
// finally, return the personalized sass
//
alert("Hey " + the_name + " " + the_insult);
}</pre>
</blockquote>
<blockquote>
<p>这种先写注释的策略不仅迫使你在写代码前思考，而且<br>
使编码的过程看起来容易些 - 通过把任务分成小的，<br>
易于编码的各个部分，你的问题看起来就不太象珠穆朗<br>
玛峰，而象一群令人愉悦的起伏的小山。</p>
</blockquote>
<p><strong>最后...</strong></p>
<p>总以分号结束你的每一条语句。</p>
<blockquote>
<p>虽然并不是严格必需，你应该养成以分号结束每一条语<br>
句的习惯，这样可以避免这行后面再有代码。忘了加<br>
分号，下一行好的代码会突然产生错误。</p>
</blockquote>
<p>把变量初始化为“var”，除非你有更好的理由不这样做。</p>
<blockquote>
<p>用“var”把变量局域化可以减少一个函数与另一个不相<br>
关函数相混淆的机会。</p>
</blockquote>
<p>好了，既然你已经知道了如何编码，下面就让我们学习怎样使<br>
你的JavaScript快速运行。<a href="day5_6.html">>></a></p>
<p align="left"><font face="宋体" size="3" color="#000000"><strong>JavaScript高级教程</strong></font><font color="#FF0000" face="宋体" size="3"><br>
</font><font color="#FF3300" size="3">第一页</font><font size="3"> </font><a href="day5_1.html"><font size="3" face="verdana, arial, geneva, sans-serif">JavaScript</font><font size="3">高级教程</font><font size="3" face="verdana, arial, geneva, sans-serif">-
</font><font size="3">第</font><font size="3" face="verdana, arial, geneva, sans-serif">5</font><font size="3">天</font></a><font size="3">
<br>
</font><font color="#FF3300" size="3">第二页 </font><font size="3"><a href="day5_2.html">打印变量</a><br>
</font><font color="#FF3300" size="3">第三页 </font><font size="3"><a href="day5_3.html">一般性程序错误</a><br>
</font><font color="#FF3300" size="3">第四页 </font><font size="3"><a href="day5_4.html">修正错误</a><br>
</font><font color="#FF3300" size="3">第五页 </font><font size="3">好的编程实践<br>
</font><font color="#FF3300" size="3">第六页 </font><font size="3"><a href="day5_6.html">按速度优化JavaScript代码</a><br>
</font><font color="#FF3300" size="3">第七页 </font><a href="day5_7.html"><font size="3">下面讲什么？</font></a></p>
<p align="left">[<a href="day1_1.html">第1课</a>][<a href="day2_1.html">第2课</a>][<a href="day3_1.html">第3课</a>][<a href="day4_1.html">第4课</a>][第5课]</p>
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