Validating phone number
Consider the following: If you are using a supported browser you can use the form below to test the regular expression: If you want to restrict the password to ONLY letters and numbers (no spaces or other characters) then only a slight change is required.Instead of using is shorthand for 'any letter, number or the underscore character'.The best thing about HTML5 attributes is that they have no effect whatsoever on unsupported browsers, so older versions of Internet Explorer will act as if they are not present and just run the Java Script validation as before.At this stage both Firefox and Opera enforce HTML5 validation attributes in the browser while Safari only lets you use them with Java Script or for CSS effects.
You might also want to spice up your forms using HTML5 Form Validation as we've done further down the page.
Another method is to display what they've entered as part of a 'confirmation page'.
The problem here is that you're making the password visible in the browser, browser cache, proxy, etc.
In most browsers - those that support Java Script 1.5 (Firefox, Chrome, Safari, Opera 7 and Internet Explorer 8 and higher) - you can use more powerful regular expressions. The code presented above is fine in that it checks everything that we wanted to check, but uses a lot of code to test each requirement individually and present different error messages.
We're going to show you now how to apply the password tests using a single regular expression.
One popular approach is to install Fail2Ban to monitor log files and lock out repeat offendors.