Javascript regular expression password validation

问题:

I am trying to validate the password using regular expression. The password is getting updated if we have all the characters as alphabets. Where am i going wrong ? is the regular expression right ?

function validatePassword() {
    var newPassword = document.getElementById('changePasswordForm').newPassword.value;
    var minNumberofChars = 6;
    var maxNumberofChars = 16;
    var regularExpression  = /^[a-zA-Z0-9!@#$%^&*]{6,16}$/;
    alert(newPassword); 
    if(newPassword.length < minNumberofChars || newPassword.length > maxNumberofChars){
        return false;
    }
    if(!regularExpression.test(newPassword)) {
        alert("password should contain atleast one number and one special character");
        return false;
    }
}

回答1:

Use positive lookahead assertions:

var regularExpression = /^(?=.*[0-9])(?=.*[!@#$%^&*])[a-zA-Z0-9!@#$%^&*]{6,16}$/;

Without it, your current regex only matches that you have 6 to 16 valid characters, it doesn't validate that it has at least a number, and at least a special character. That's what the lookahead above is for.

• (?=.*[0-9]) - Assert a string has at least one number;
• (?=.*[!@#$%^&*]) - Assert a string has at least one special character.

回答2:

function validatePassword() {
    var p = document.getElementById('newPassword').value,
        errors = [];
    if (p.length < 8) {
        errors.push("Your password must be at least 8 characters"); 
    }
    if (p.search(/[a-z]/i) < 0) {
        errors.push("Your password must contain at least one letter.");
    }
    if (p.search(/[0-9]/) < 0) {
        errors.push("Your password must contain at least one digit."); 
    }
    if (errors.length > 0) {
        alert(errors.join("\n"));
        return false;
    }
    return true;
}

There is a certain issue in below answer as it is not checking whole string due to absence of [ ] while checking the characters and numerals, this is correct version

回答3:

you can make your own regular expression for javascript validation

    /^            : Start
    (?=.{8,})        : Length
    (?=.*[a-zA-Z])   : Letters
    (?=.*\d)         : Digits
    (?=.*[!#$%&? "]) : Special characters
    $/              : End



        (/^
        (?=.*\d)                //should contain at least one digit
        (?=.*[a-z])             //should contain at least one lower case
        (?=.*[A-Z])             //should contain at least one upper case
        [a-zA-Z0-9]{8,}         //should contain at least 8 from the mentioned characters

        $/)

Example:-   /^(?=.*\d)(?=.*[a-zA-Z])[a-zA-Z0-9]{7,}$/

回答4:

I use the following script for min 8 letter password, with at least a symbol, upper and lower case letters and a number

function checkPassword(str)
{
    var re = /^(?=.*\d)(?=.*[!@#$%^&*])(?=.*[a-z])(?=.*[A-Z]).{8,}$/;
    return re.test(str);
}

回答5:

Don't try and do too much in one step. Keep each rule separate.

function validatePassword() {
    var p = document.getElementById('newPassword').value,
        errors = [];
    if (p.length < 8) {
        errors.push("Your password must be at least 8 characters");
    }
    if (p.search(/[a-z]/i) < 0) {
        errors.push("Your password must contain at least one letter."); 
    }
    if (p.search(/[0-9]/) < 0) {
        errors.push("Your password must contain at least one digit.");
    }
    if (errors.length > 0) {
        alert(errors.join("\n"));
        return false;
    }
    return true;
}

回答6:

If you check the length seperately, you can do the following:

var regularExpression  = /^[a-zA-Z]$/;

if (regularExpression.test(newPassword)) {
    alert("password should contain atleast one number and one special character");
    return false;
}