Validation using javascript
A lot of websites now require registration, which means that users are either assigned a username and password, or get to select one. Here are some simple steps that will make the process a bit more secure:
Use the “password” input type:
Instead of <input type=”text”> you should always use <input type=”password”> as this lets the browser (and the user) know that the contents of that field need to be secured.
Enforcing ’strong’ passwords:
Some common restrictions are-
• at least n characters
• combination of upper- and lower-case characters
• one or more digits
• not related to other user data (name, address, username, …)
All of these are possible using javascript.
function checkForm(form) {
if(form.username.value == “”) {
alert(“Error: Username cannot be blank!”);
form.username.focus();
return false;
}
re = /^\w+$/;
if(!re.test(form.username.value))
{
alert(“Error: Username must contain only letters, numbers and underscores!”);
form.username.focus();
return false;
}
if(form.pwd1.value != “” && form.pwd1.value == form.pwd2.value) {
if(form.pwd1.value.length < 6) {
alert(“Error: Password must contain at least six characters!”);
form.pwd1.focus();
return false;
}
if(form.pwd1.value == form.username.value) {
alert(“Error: Password must be different from Username!”);
form.pwd1.focus();
return false;
}
re = /[0-9]/;
if(!re.test(form.pwd1.value)) {
alert(“Error: password must contain at least one number (0-9)!”);
form.pwd1.focus();
return false;
}
re = /[a-z]/;
if(!re.test(form.pwd1.value)) {
alert(“Error: password must contain at least one lowercase letter (a-z)!”);
form.pwd1.focus();
return false;
}
re = /[A-Z]/;
if(!re.test(form.pwd1.value)) {
alert(“Error: password must contain at least one uppercase letter (A-Z)!”);
form.pwd1.focus();
return false;
}
} else {
alert(“Error: Please check that you’ve entered and confirmed your password!”);
form.pwd1.focus();
return false;
}
alert(“You entered a valid password: ” + form.pwd1.value);
return true;
}
</script>
(Excerpted from: http://www.the-art-of-web.com/javascript/validate-password/)
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