Restricting text boxes with regular expressions you can only enter numbers, decimal points, English letters, Chinese characters, etc. regular expressions

restricting text boxes with regular expressions can only enter numbers, decimal points, English letters, Chinese characters and other types of code

<input onkeyup= "This.value=this.value.replace (/\d/g,") "Onafterpaste=" This.value=this.value.replace (/\D/g, " ) ">

2. Only numbers can be entered and the decimal point may be lost.
<input onkeyup= "if (isNaN (value)) ExecCommand (' Undo ') ' onafterpaste= ' if (isNaN (value)) ExecCommand (' Undo ') >
<input name=txt1 onchange= "if (/\d/.test (this.value)) {alert (' can only enter numbers '); this.value= ';} ' >

3. Number and decimal method two
<input type=text t_value= "" o_value= "" onkeypress= "if!this.value.match (/^[\+\-]?\d*?\.? \d*?$/)) This.value=this.t_value;else this.t_value=this.value;if (This.value.match/^ (?: [\+\-]?\d+ (?: \. \d+)? $/)) This.o_value=this.value "onkeyup=" if (!this.value.match/^[\+\-]?\d*?\.? \d*?$/)) This.value=this.t_value;else this.t_value=this.value;if (This.value.match/^ (?: [\+\-]?\d+ (?: \. \d+)? $/)) This.o_value=this.value "onblur=" if (!this.value.match (?: [/^ (?: \. \d+)? | \.\d*?)? $/)) this.value=this.o_value;else{if (This.value.match (/^\.\d+$/)) this.value=0+this.value;if (This.value.match (/^ \.$/)) This.value=0;this.o_value=this.value} ">

4. Only letters and characters can be entered
<input onkeyup= "Value=value.replace (/[\d]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[\d]/g, ') "maxlength=10 name=" Numbers ">

5. Can only enter English letters and numbers, can not enter Chinese
<input onkeyup= "Value=value.replace (/[^\w\.\/]/ig, ')" >

6. Only digital and English <font color= "Red" >chun</font>
<input onkeyup= "Value=value.replace (/[^\d|chun]/g, ')" >

7. Only a maximum of two digits after the decimal point (number, Chinese can be entered), can not enter letters and operational symbols:
<input onkeypress= "If" (event.keycode<48 | | event.keycode>57) && event.keycode!=46 | |/\.\d\d$/.test ( Value)) Event.returnvalue=false ">

8. After the decimal point can only have up to two digits (numbers, letters, Chinese can be entered), you can enter operational symbols:
<input onkeyup= "This.value=this.value.replace (/^ (\-) * (\d+) \. ( \d\d). *$/, ' $1$2.$3 ') >

Only numbers can be entered: "^[0-9]*$".
Only n digits can be entered: "^\d{n}$".
You can enter at least n digits: "^\d{n,}$".
You can enter only the number of m~n digits:. "^\d{m,n}$"
Only numbers beginning with 0 and not 0 can be entered: ^ (0|[ 1-9][0-9]*) $ ".
You can only enter positive real numbers with two decimal digits: ^[0-9]+ (. [ 0-9]{2})? $ ".
You can only enter positive real numbers with 1~3 decimal places: ^[0-9]+ (. [ 0-9]{1,3})? $ ".
You can only enter a Non-zero positive integer: "^\+?" [1-9] [0-9]*$].
You can only enter a Non-zero negative integer: "^\-[1-9][]0-9" *$.
You can only enter characters with a length of 3: "^. {3}$ ".

You can only enter a string of 26 English letters: "^[a-za-z]+$".
You can only enter a string consisting of 26 uppercase letters: "^[a-z]+$".
You can only enter a string consisting of 26 lowercase English letters: "^[a-z]+$".
You can only enter a string consisting of numbers and 26 English letters: "^[a-za-z0-9]+$".
You can only enter a string of numbers, 26 English letters, or underscores: "^\w+$".

Verify user password: "^[a-za-z]\w{5,17}$" is in the correct format: begins with a letter, length between 6~18, and can only contain characters, numbers, and underscores. &NBSP
Verify that ^%& ',; =?$\ ' characters are included: "[^%& ',; =?$\x22]+". &NBSP
Only Kanji can be entered: "^[\u4e00-\u9fa5]{0,}$"  
Verify email Address: "^\w+ ([-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *$ ". &NBSP
Verify InternetURL: "^http://([\w-]+\.) +[\w-]+ (/[\w-./?%&=]*)? $ ". &NBSP
Verify Phone Number: "^ (\d{3,4}-) |\d{3.4}-)? \d{7,8}$" The correct format is: "Xxx-xxxxxxx", "xxxx-xxxxxxxx", "xxx-xxxxxxx", " Xxx-xxxxxxxx "," XXXXXXX "and" XXXXXXXX ". &NBSP
Verify the identity card number (15-bit or 18-digit number): "^\d{15}|\d{18}$". &NBSP
Verify 12 months of the year: "^ (0?[ 1-9]|1[0-2]) $ "The correct format is:" 01 "~" 09 "and" 1 "~" 12 ". &NBSP
Verify one month 31 days: "^ (0?[ 1-9]) | ((1|2) [0-9]) |30|31) $ "the correct format is;" 01 "~" 09 "and" 1 "~" 31 ".

Use regular expressions to restrict the entry of text boxes in a Web page's form:
Only Chinese can be entered with regular expression restrictions:
Only full-width characters can be entered with regular expression restrictions:
Only numbers can be entered with regular expression restrictions:
You can only enter numbers and English with regular expression restrictions:
You have to use regular expressions to extract the filename from the URL address of the JavaScript program, the following result is Page1
S= "Http://www.slfans.com"
S=s.replace (/(. *\/) {0,} ([^\.] +). */ig, "$"
Alert (s)
Match Double-byte characters (including Chinese characters): [^\x00-\xff]
Application: Computes the length of the string (a double-byte character length meter 2,ascii character 1)
String.prototype.len=function () {return This.replace ([^\x00-\xff]/g, "AA"). Length;}
A regular expression that matches a blank row: \n[\s|] *\r
Regular expression matching HTML tags:/< (. *) >.*<\/\1>|< (. *) \/>/
Matching a regular expression with a trailing space: (^\s*) | (\s*$)
String.prototype.trim = function ()
{
Return This.replace (/(^\s*) | ( \s*$)/g, "");
}

To decompose and transform an IP address using a regular expression:
The following is a JavaScript program that uses a regular expression to match an IP address and converts an IP address to a corresponding numeric value:
function IP2V (IP)
{
re=/(\d+) \. (\d+) \. (\d+) \. (\d+)/g//matching the regular expression of the IP address
if (Re.test (IP))
{
Return Regexp.$1*math.pow (255,3)) +regexp.$2*math.pow (255,2)) +regexp.$3*255+regexp.$4*1
}
Else
{
throw new Error ("not a valid IP address!")
}
}
However, if the above program does not use a regular expression, and the split function directly to decompose may be simpler, the program is as follows:
var ip= "10.100.20.168"
Ip=ip.split (".")
Alert ("IP value is:" + (IP[0]*255*255*255+IP[1]*255*255+IP[2]*255+IP[3]*1))
Symbolic Explanation:
Character description
\ marks the next character as a special character, or a literal character, or a backward reference, or a octal escape character.
For example, ' n ' matches the character ' n '. ' \ n ' matches a newline character. Sequence ' \ ' matches ' \ ' and ' \ (' Matches ' (".
^ matches the start position of the input string. If the Multiline property of the RegExp object is set, ^ also matches the position after ' \ n ' or ' \ R '.
$ matches the end position of the input string. If the Multiline property of the RegExp object is set, the $ also matches the position before ' \ n ' or ' \ R '.
* Match the preceding subexpression 0 or more times. For example, zo* can match "z" and "Zoo". * is equivalent to {0,}.
+ matches the preceding subexpression one or more times. For example, ' zo+ ' can match "Zo" and "Zoo", but cannot match "Z". + is equivalent to {1,}.
? Match the preceding subexpression 0 times or once. For example, "Do (es)" can match "do" in "do" or "does". is equivalent to {0,1}.
{n} n is a non-negative integer. Matches the determined n times. For example, ' o{2} ' cannot match ' o ' in ' Bob ', but can match two o in ' food '.
{N,} n is a non-negative integer. Match at least n times. For example, ' o{2,} ' cannot match ' o ' in ' Bob ' but can match all o in ' Foooood '. ' O{1,} ' is equivalent to ' o+ '. ' O{0,} ' is equivalent to ' o* '.
{n,m} m and n are non-negative integers, where n <= m. Matches n times at least and matches up to M times. For example, "o{1,3}" will match the first three o in "Fooooood". ' o{0,1} ' is equivalent to ' o '. Notice that there is no space between the comma and the two number.
? When the character is immediately following any of the other qualifiers (*, +,?, {n}, {n,}, {n,m}), the matching pattern is not greedy. Non-greedy patterns match as few strings as possible, while the default greedy pattern matches as many of the searched strings as possible. For example, for the string "oooo", ' o+? ' will match a single "O", and ' o+ ' will match all ' o '.
. Matches any single character except "\ n". To match any character including ' \ n ', use a pattern like ' [. \ n] '.
(pattern) matches the pattern and gets the match. The obtained matches can be obtained from the resulting matches collection, use the Submatches collection in VBScript, and use the $0...$9 property in JScript. To match the parentheses character, use ' \ (' or ' \ ').
(?:p Attern) matches pattern but does not get matching results, which means that this is a non fetch match and is not stored for later use. This is useful for combining parts of a pattern with the "or" character (|). For example, ' Industr (?: y|ies) is a more abbreviated expression than ' industry|industries '.
(? =pattern) forward lookup, matching the find string at the beginning of any string matching pattern. This is a non-fetch match, that is, the match does not need to be acquired for later use. For example, ' Windows (? =95|98| nt|2000) ' Can match windows in Windows 2000, but cannot match windows in Windows 3.1. It does not consume characters, that is, after a match occurs, the next matching search begins immediately after the last match, instead of starting after the character that contains the pre-check.
(?! pattern), which matches the lookup string at the beginning of any string that does not match the pattern. This is a non-fetch match, that is, the match does not need to be acquired for later use. For example, ' Windows (?! 95|98| nt|2000) ' Can match windows in Windows 3.1, but cannot match windows in Windows 2000. It does not consume characters, that is, after a match occurs, the next matching search begins immediately after the last match, instead of starting after the character that contains the pre-check.
X|y matches x or Y. For example, ' Z|food ' can match "z" or "food". ' (z|f) Ood ' matches ' zood ' or ' food '.
[XYZ] Character set combination. Matches any one of the characters contained. For example, ' [ABC] ' can match ' a ' in ' plain '.
[^XYZ] Negative character set combination. Matches any characters that are not included. For example, ' [^ABC] ' can match ' P ' in ' plain '.
[A-z] character range. Matches any character within the specified range. For example, ' [A-z] ' can match any lowercase alphabetic character in the range ' a ' to ' Z '.
[^a-z] a negative character range. Matches any character that is not in the specified range. For example, ' [^a-z] ' can match any character that is not in the range of ' a ' to ' Z '.
\b Matches a word boundary, which refers to the position between the word and the space. For example, ' er\b ' can match ' er ' in ' never ', but cannot match ' er ' in ' verb '.
\b Matches a non word boundary. ' er\b ' can match ' er ' in ' verb ', but cannot match ' er ' in ' Never '.
\CX matches the control characters indicated by X. For example, \cm matches a control-m or carriage return character. The value of x must be one-a-Z or a-Z. Otherwise, c is treated as a literal ' C ' character.
\d matches a numeric character. equivalent to [0-9].
\d matches a non-numeric character. equivalent to [^0-9].
\f matches a page feed character. Equivalent to \x0c and \CL.
\ n matches a newline character. Equivalent to \x0a and \CJ.
\ r matches a carriage return character. Equivalent to \x0d and \cm.
\s matches any white space character, including spaces, tabs, page breaks, and so on. equivalent to [\f\n\r\t\v].
\s matches any non-white-space character. equivalent to [^ \f\n\r\t\v].
\ t matches a tab character. Equivalent to \x09 and \ci.
\v matches a vertical tab. Equivalent to \x0b and \ck.
\w matches any word character that includes an underscore. Equivalent to ' [a-za-z0-9_] '.
\w matches any non word character. Equivalent to ' [^a-za-z0-9_] '.
\XN matches N, where n is the hexadecimal escape value. The hexadecimal escape value must be a determined two digits long. For example, ' \x41 ' matches ' A '. ' \x041 ' is equivalent to ' \x04 ' & ' 1 '. You can use ASCII encoding in regular expressions ...
\num matches num, where num is a positive integer. A reference to the match that was obtained. For example, ' (.) \1 ' matches two consecutive identical characters.
\ n identifies a octal escape value or a backward reference. n is a backward reference if you have at least n obtained subexpression before \ nthe. Otherwise, if n is an octal number (0-7), then N is an octal escape value.
\NM identifies a octal escape value or a backward reference. NM is a backward reference if at least NM has obtained the subexpression before \nm. If there are at least N fetches before \nm, then n is a backward reference followed by a literal m. If all the preceding conditions are not satisfied, if both N and M are octal digits (0-7), then \nm will match octal escape value nm.
\NML if n is an octal number (0-3) and both M and L are octal digits (0-7), then the octal escape value NML is matched.
\un matches N, where N is a Unicode character represented in four hexadecimal digits. For example, \u00a9 matches the copyright symbol (?).