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javascript 学习笔记——String
记录以下网址的javascript core crash章节http://courses.coreservlets.com/Course-Materials/ajax-basics.html
1、String常用
2、String、Number互相转换
3、正则表达式
正则表达式中的特殊字符(同组内以逗号隔开):
引用- – ^, $, . – beginning, end of string, any one char ,
- – \ – escape what would otherwise be a special character
- – *, +, ? – 0 or more, 1 or more, 0 or 1 occurrences
- – {n} {n } – exactly n n or more occurrences {n}, {n,} exactly n, n or more occurrences
- – [] – grouping
- – \s, \S – whitespace, non-whitespace
- \w \W word char (letter or number) non word char – \w, \W – word char (letter or number), non-word char
复制代码 正则表达式的选项:
引用
– /pattern/g – do global matching (find all matches, not just first one)
– /pattern/i – do case-insensitive matching
– /pattern/m – do multiline matching
本文源代码:
Html代码- <!-- LCTestJS_String.html version: 2012_01_11 -->
- <!DOCTYPE html PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
- <html>
- <head>
- <meta http-equiv="Content-Type" content="text/html; charset=UTF-8">
- <title>测试javascript 的string version: 2012_01_11</title>
- <style>
- h3 {
- color: #FFF;
- background-color: #09F;
- font-style: normal;
- font-weight: bold;
- }
-
- h4 {
- font-weight: bolder;
- color: #d00;
- background-color: #CCC;
- }
- </style>
-
- </head>
- <body>
-
- <h2>测试javascript 的string version: 2012_01_11</h2>
-
- <h3>String——常用的</h3>
- <h4>
- 单引号双引号均可
- <p>用==判断两个字符串内容是否相同</p>
- </h4>
- <script type="text/javascript">
- var strDoubleQuotes = "asdf";
- var strSingleQuote = 'asdf';
- var isEqual = strDoubleQuotes == strSingleQuote;
- document.write("<p>\"asdf\"=='asdf'?\t" + isEqual);
- </script>
-
- <h4>.length属性:字符串长度</h4>
- <script type="text/javascript">
- document.write("<p>'asdf'.length=\t" + 'asdf'.length);
- </script>
-
-
-
- <h4>常用函数:类似java</h4>
- charAt, indexOf, lastIndexOf, substring, toLowerCase, toUpperCase
-
- <h4>html专用函数(非标准)</h4>
- <script type="text/javascript">
- 'test'.bold().italics().fontcolor('red')
- document.write("<p>'test'.bold().italics().fontcolor('red')="
- + 'test'.bold().italics().fontcolor('red'));
- </script>
-
- <h3>String,Number互相转换</h3>
- <h4>
- Number转String: .toFixed(num):按num保留小数点后的位数(四舍五入)
- <p>可以通过new String(arg)来明确声明为String类型(其他类型类似)</p>
- </h4>
- <script type="text/javascript">
- document.write("<p>(1.236).toFixed(2)=\t" + (1.236).toFixed(2));
- var n = 1.236;
- document.write("<p>(1.236).length=\t" + n.length);
- document.write("<p>(1.236).toFixed(2).length=\t"
- + (1.236).toFixed(2).length);
- document.write("<p>new String(1.236).length=\t"
- + new String(1.236).length);
- </script>
-
- <h4>String转Number;从第一个字母开始被忽略</h4>
- <script type="text/javascript">
- var s = new String('1234ff');
- document.write("<p>parseInt('12.34ff')=" + parseInt('12.34ff'));
- document.write("<p>parseInt('12.34ff', 2)=" + parseInt('12.34ff', 2)
- + "\t错了吧?");
- document.write("<p>parseInt('12.34ff', 3)=" + parseInt('12.34ff', 3));
- document.write("<p>parseInt('12.34ff', 4)=" + parseInt('12.34ff', 4));
- document.write("<p>parseInt('12.34ff', 5)=" + parseInt('12.34ff', 5));
- document.write("<p>----");
- document.write("<p>parseFloat('12.34ff')=" + parseFloat('12.34ff'));
- </script>
-
- <h3>正则表达式</h3>
- <h4>
- 正则表达式: 用在两个斜杠(/表达式/)中间的式子,而非String来表示
- <p>可用于函数:match, replace, search, split</p>
- </h4>
- <script type="text/javascript">
- document.write("<p>'testABCDABCabc'.split(/A/)="
- + 'testABCDABCabc'.split(/A/)
- + "\t结果是数组,直接输出以逗号隔开,可以自己用for语句输出");
- //var splited='testABCDABCabc'.split(/A/);
- //for(var i=0;i<splited.length;i++){
- // document.write("<p>"+splited[i]);
- //}
- document.write("<p>'testABCDABCabc'.split(/A/i)="
- + 'testABCDABCabc'.split(/A/i) + "\t加个选项i,就变成大小写不敏感了");
- </script>
-
- </body>
- </html>
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