JavaScript regular expression profiles and use case

JS Regular Description:
     RegExp object represents a regular expression, it is a powerful tool for the implementation of the string pattern matching. A regular expression is a character sequence of search mode. The search mode can be used to replace text search and text operations.
    Example:

var patt = /w3school/i;
//  /w3school/是搜索模式;i（对搜索模式中的字母大小写不敏感）
//最后包含属性 "g"、"i" 和 "m"，分别用于指定全局匹配、区分大小写的匹配和多行匹配

Direct amount syntax: / pattern / the Attributes
create RegExp object syntax: new new RegExp (pattern, the Attributes); // parameter pattern is a string that specifies a regular expression pattern or other regular expression. optional attributes is a string that contains the attribute "g", "i" and "m", are used to specify the global matching insensitive matching and multi-line matching.

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Canonical correlation:
Square brackets:

Square brackets are used to find a range of characters:

expression	description
[abc]	Find any character between the brackets.
[^abc]	Find any character not between the brackets.
[0-9]	Find any digit from 0 to 9.
[a-z]	Find any character from lowercase a to lowercase z's.
[A-Z]	Find any character from uppercase A to Z of capital.
[A-z]	Z Find any character from uppercase A to lowercase.
[Adgk]	Finding given to any character in the set.
[^ Adgk]	Find character given to anyone outside the set.
(red|blue|green)	Find any options specified.

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Regular metacharacters:

Metacharacter (Metacharacter) is to have a special meaning of characters:

Metacharacters	description
.	Find a single character, except for line breaks and line endings.
\w	Find a word character.
\W	Find a non-word character.
\d	Find figures.
\D	Finding non-numeric characters.
\s	Find a blank character.
\S	Find a non-whitespace characters.
\b	Match a word boundary.
\B	Matching non-word boundary.
\0	Find NUL characters.
\n	Find newline.
\f	Find feed character.
\r	Find carriage return.
\t	Find tab.
\ v	Find vertical tab.
\xxx	Find octal number xxx defined characters.
\ xdd	Find a hexadecimal number dd illegal characters.
\ uxxxx	Find a hexadecimal number xxxx provisions of Unicode characters.

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Regular quantifiers:

quantifier	description
n+	Matches any string containing at least one of n (one or more times).
n*	Matches any string contains zero or more occurrences of n.
n?	Matches any zero or a string containing n.
n{X}	Matching string comprising the sequence of X n.
n {X, Y}	It contains the string matching sequence X to Y number of n.
n{X,}	X matching string comprising at least a sequence of n.
n$	Matches any string of n ends.
^n	Matches any string that begins with n.
?=n	Immediately followed by the specified string matches any character string n.
?!n	Immediately thereafter not match any character string specified string n.

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RegExp object methods:

method	description	FF	IE
compile	Compiling a regular expression.	1	4
exec	Value specified in the search character string. The return value of the find and determine its location.	1	4
test	Value specified in the search character string. Returns true or false.	1	4

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It supports regular expressions String object methods

method	description	FF	IE
search	Retrieving the value of the regular expression to match.	1	4
match	Find one or more regular expression matching.	1	4
replace	Alternatively substring match the regular expression.	1	4
split	String is divided into an array of strings.	1	4

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JS regular Example

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Determine the user's input is not a valid phone number?

                //test检验是否符合特定规范
                //定义正则表达式
                var phone = document.getElementById("txtphone").value;
                //var msgstr = /^[0-9]{11}/;
                //var result=msgstr.test(phone);//检验是否符合特定格式
                //alert(result);
                var msgstr = /\d{11}/g;//设置为全局变量，用于全部循环检索(实现原理：会记录查找到的索引位置和长度，跳过依次查询)
                var result = msgstr.exec(msg);//默认只返回第一个结果，所以要循环输出
                while (result) {//只要不是null或underfined就是找到结果了就是为True
                   // alert(result);//打印该值
                    result = msgstr.exec(msg);
                };

Determine whether the mailbox user input is valid?

                //邮箱格式检索
                var emailstr = /\w+\.\w+@\w+\.(\w+)+/;
                var res=emailstr.test(phone);
                //alert(res);

Regular grouping queries:

                //分组查询
                var groupstr = /(\d{3})\d{4}(\d{4})/g;
                var str = groupstr.exec(msg);
                //结果第一组是匹配的字符串，第二组是第一个匹配，第三组是第二个匹配
                //alert(str.toString());//13013582532  130  1358

String using regular expressions string substitution:

                //字符串的替换
                var results=msg.replace(/(\d{3})(\d{4})(\d{4})/g, '$1****$3');//$1指定字符串第一部分原样输出
                //alert(results);

String uses regular expressions to remove the spaces on both sides:

                //去除两端空格
                var msgstr = "       hellow         ";
                //将前后的空白换成空字符，空字符如果加空格就一个字符否则就是空字符也是去空格
                var resstr = msgstr.replace(/^\s+/, '').replace(/\s+$/, '');
                //
                var s=msgstr.trim();//实现02
                alert(s);