If循环IfIf-elseIf嵌套
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">var d=new Date();var time= d.getHours();if(time<10){document.write("早上好！");}</script></head><body><h1>if的示例（1_1）</h1>1,if(条件1){语句1:}</pre><p>如果我们的浏览器的时间在10点之前，我们将得到一个"早上好！" 的问候。</p></body></html>
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">var d=new Date();var time= d.getHours();if(time<=10){document.write("早上好！");}else if(time<=12){document.write("上午好！");}else if(time<=18){document.write("下午好！");}else{document.write("晚上好！");}</script></head><body><h1>if的示例(1_2)</h1><pre>2，if(条件1){语句1:}esle{语句2:}</pre><p>根据浏览器不同的时间段：提示相应的问候语。</p></body></html>
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">var i=j=1;var k=2;if(i==j){if(j==k){document.write("j等于k");}else{document.write("j不等于k");}}</script></head><body><h1>嵌套if语句（1_3）</h1><h2><pre>公式：3,if(条件1){if(条件2){语句1:}}</pre></h2></body></html>
forswitchwhiledo-while
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">for(var i=1;i<=5;i=i+1){document.write(i);document.write("<br>");}</script></head><body><h1>for循环示例</h1><pre>利用for循环输出1-5之间的数字。for(初始值;条件; 增值){语句块1;}</pre></body></html>
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">var d=new Date();theDay=d.getDay();document.write("今天是周",theDay,",");switch(theDay){case 5:document.write("<b>今天是周五</b>");break;case 6:document.write("<b>今天是周六</b>");break;default:document.write("<b>工作日，我们期待周末的到来！嘿嘿</b>");}</script></head><body><h1>switch循环示例</h1><h2><pre>基本格式：switch(条件){case label1:语句段1;break;case label2:语句段2;break;case label3:语句段3;break;...... default:语句段 4；}</pre></h2></body></html>
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">var count=0;while(count<10){document.write(count+"<br>");count++;}</script></head><body><h1>while循环示例</h1><h2>当条件为真是时，重复循环，否则退出循环体。</h2><pre>while(判断条件1){语句块1;}</pre></body></html>
<html xmlns="/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=gb2312" /><title>无标题文档</title><script language="javascript">var count =0;do{document.write(count+"<br>");count++;}while(count<0)</script></head><body><h1>do while循环的示例</h1><h2><pre>基本格式：do{语句段;}while(条件)例如：即使条件永远不为真，循环中的语句至少也会执行一次。</pre></h2></body></html>
