javascript 学习笔记——String

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#javascript #string #正则表达式 #ViewUI

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本文详细介绍了JavaScript中的String操作、Number与String的转换方法及正则表达式的使用技巧。通过实例演示了字符串的创建、属性和方法，如length、charAt等，并展示了如何利用正则表达式进行文本匹配。

[size=medium]记录以下网址的javascript core crash章节[url]http://courses.coreservlets.com/Course-Materials/ajax-basics.html[/url][/size]

[b][size=x-large]1、String常用[/size][/b]
[size=medium]下面说有错的地方其实没错，因为二进制里面不存在2这个字符啊，只有0和1！！！[/size]
[align=center][img]http://dl.iteye.com/upload/attachment/0061/9792/0974b4b5-d92e-3748-abf3-378776d60f60.png[/img][/align]
[b][size=x-large]2、String、Number互相转换[/size][/b]

[align=center][img]http://dl.iteye.com/upload/attachment/0061/9794/80c3bf96-53ca-3a3f-b20e-02a8c2140daa.png[/img][/align]

[b][size=x-large]3、正则表达式[/size][/b]
[size=large]正则表达式中的特殊字符（同组内以逗号隔开）：[/size]
[quote]
– ^, $, . – 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
[/quote]

[size=large]正则表达式的选项：[/size]
[quote]
– /pattern/g – do global matching (find all matches, not just first one)
– /pattern/i – do case-insensitive matching
– /pattern/m – do multiline matching
[/quote]

[align=center][img]http://dl.iteye.com/upload/attachment/0061/9796/6ca986bd-539d-3eed-bd06-68c934b316ee.png[/img][/align]

[size=large]本文源代码：[/size]


<!-- 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>