A regular expression that matches URL URLs: http://([\w-]+\.) +[\w-]+ (/[\w-/?%&=]*)?
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Here is an example:
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, ') "
1. 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, ') "
2. 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, ') "
3. Only numbers and English can be entered using regular expression restrictions: onkeyup= "Value=value.replace (/[\w]/g,") "Onbeforepaste=" Clipboarddata.setdata (' text ', Clipboarddata.getdata (' text '). Replace (/[^\d]/g, ') "
4. Calculate the length of the string (a double-byte character length meter 2,ascii character count 1)
To decompose and transform an IP address using a regular expression:
6. The following is a JavaScript program that uses regular expressions 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 correct 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))
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