Regular expression pattern matching Javascript

Regular expression pattern matching Javascript
Summary: Collects some commonly used regular expressions.
Regular expressions are used for string processing, form validation, and so on, practical and efficient, but often not too sure to use, so it is always necessary to search the Internet. I've collected some commonly used expressions here for the purposes of my memo. This post will be updated at any time.

Matching regular expressions for Chinese characters: [\U4E00-\U9FA5]

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*$)

Application: JavaScript does not have a trim function like VBScript, we can use this expression to implement, as follows:

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))

Regular expression matching an email address: \w+ ([-+.] \w+) *@\w+ ([-.] \w+) *\.\w+ ([-.] \w+) *

A regular expression that matches URL URLs: http://([\w-]+\.) +[\w-]+ (/[\w-/?%&=]*)?

Using regular expressions to remove the repeated characters in the string algorithm program: [Note: This program is incorrect, the reason see this post reply]

var s= "Abacabefgeeii"
var s1=s.replace (/(.). *\1/g, "$")
var re=new RegExp ("[" +s1+ "]", "G")
var s2=s.replace (Re, "")
Alert (S1+S2)//Result: ABCEFGI

I used to post on the csdn to find an expression to achieve the elimination of repeated characters, and ultimately did not find, this is the simplest way I can think of implementation. The idea is to use a back reference to take out the characters that contain duplicates, and then to create a second expression with a repeating character, with a concatenation of the characters that are not repeated. This method may not apply to strings that are required for character order.

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.9499.net/page1.htm"
S=s.replace (/(. *\/) {0,} ([^\.] +). */ig, "$"
Alert (s)

Use regular expressions to restrict the entry of text boxes in a Web page's form:

The regular expression limit can only be entered in Chinese: onkeyup= "value=value.replace (/[^\u4e00-\u9fa5]/g,") "Onbeforepaste=" Clipboarddata.setdata (' Text ', Clipboarddata.getdata (' text '). Replace (/[^\u4e00-\u9fa5]/g, ') "

Only full-width characters can be entered with regular expression restrictions: onkeyup= "Value=value.replace (/[^\uff00-\uffff]/g,") "Onbeforepaste=" Clipboarddata.setdata (' Text ', Clipboarddata.getdata (' text '). Replace (/[^\uff00-\uffff]/g, ') "

Only numbers can be entered with regular expression restrictions: onkeyup= "Value=value.replace (/[^\d]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[^\d]/g, ') "

Only numbers and English can be entered with regular expression restrictions: onkeyup= "Value=value.replace (/[\w]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[^\d]/g, ') "