validator

What is validator?

The validator npm package is a library of string validators and sanitizers. It provides a variety of functions to validate and sanitize strings, such as checking if a string is in a certain format (e.g., email, URL) or transforming strings to ensure they are safe for use in different contexts.

What are validator's main functionalities?

Email Validation

Checks if the input string is an email.

const validator = require('validator');
console.log(validator.isEmail('[e-mail]')); // true

URL Validation

Checks if the input string is a URL.

const validator = require('validator');
console.log(validator.isURL('https://www.example.com')); // true

Sanitizing Strings

Escapes HTML characters in the input string to prevent XSS attacks.

const validator = require('validator');
console.log(validator.escape('<script>alert("xss")</script>')); // '&lt;script&gt;alert(&quot;xss&quot;)&lt;/script&gt;'

Checking String Length

Checks if the input string's length falls within a specified range.

const validator = require('validator');
console.log(validator.isLength('Hello', {min: 2, max: 10})); // true

Blacklisting Characters

Removes specified characters from the input string.

const validator = require('validator');
console.log(validator.blacklist('abc123', '123')); // 'abc'

Other packages similar to validator

joi

Joi is a powerful schema description language and data validator for JavaScript. It allows for a more detailed and structured validation process compared to validator, including the ability to create custom validation schemas.

yup

Yup is a JavaScript schema builder for value parsing and validation. It uses a schema-based approach similar to Joi and can be integrated with form libraries like Formik. It is more focused on object schema validation.

class-validator

Class-validator works with classes and decorators to validate that the properties of an object conform to specified rules. It is typically used with TypeScript and integrates well with class-based frameworks like TypeORM.

express-validator

Express-validator is a set of express.js middlewares that wraps validator.js functions. It is specifically designed for use with the Express web application framework and allows for easy integration of validation into the request processing pipeline.

README

node-validator is a library of string validation, filtering and sanitization methods.

To install node-validator, use npm:

$ npm install validator

To use the library in the browser, include validator-min.js

Example

var check = require('validator').check,
    sanitize = require('validator').sanitize

//Validate
check('[e-mail]').len(6, 64).isEmail();        //Methods are chainable
check('abc').isInt();                                //Throws 'Invalid integer'
check('abc', 'Please enter a number').isInt();       //Throws 'Please enter a number'
check('abcdefghijklmnopzrtsuvqxyz').is(/^[a-z]+$/);

//Sanitize / Filter
var int = sanitize('0123').toInt();                  //123
var bool = sanitize('true').toBoolean();             //true
var str = sanitize(' \s\t\r hello \n').trim();       //'hello'
var str = sanitize('aaaaaaaaab').ltrim('a');         //'b'
var str = sanitize(large_input_str).xss();
var str = sanitize('&lt;a&gt;').entityDecode();      //'<a>'

Web development

Often it's more desirable to check or automatically sanitize parameters by name (rather than the actual string). See this gist for instructions on binding the library to the request prototype.

If you are using the express.js framework you can use the express-validator middleware to seamlessly integrate node-validator.

Example http://localhost:8080/?zip=12345&foo=1&textarea=large_string

get('/', function (req, res) {
    req.onValidationError(function (msg) {
        //Redirect the user with error 'msg'
    });

    //Validate user input
    req.check('zip', 'Please enter a valid ZIP code').len(4,5).isInt();
    req.check('email', 'Please enter a valid email').len(6,64).isEmail();
    req.checkHeader('referer').contains('localhost');

    //Sanitize user input
    req.sanitize('textarea').xss();
    req.sanitize('foo').toBoolean();

    //etc.
});

List of validation methods

is()                            //Alias for regex()
not()                           //Alias for notRegex()
isEmail()
isUrl()                         //Accepts http, https, ftp
isIP()
isAlpha()
isAlphanumeric()
isNumeric()
isInt()                         //isNumeric accepts zero padded numbers, e.g. '001', isInt doesn't
isLowercase()
isUppercase()
isDecimal()
isFloat()                       //Alias for isDecimal
notNull()
isNull()
notEmpty()                      //i.e. not just whitespace
equals(equals)
contains(str)
notContains(str)
regex(pattern, modifiers)       //Usage: regex(/[a-z]/i) or regex('[a-z]','i')
notRegex(pattern, modifiers)
len(min, max)                   //max is optional
isUUID(version)                 //Version can be 3 or 4 or empty, see http://en.wikipedia.org/wiki/Universally_unique_identifier
isDate()                        //Uses Date.parse() - regex is probably a better choice
isAfter(date)                   //Argument is optional and defaults to today
isBefore(date)                  //Argument is optional and defaults to today
isIn(options)                   //Accepts an array or string
notIn(options)
max(val)
min(val)
isArray()
isCreditCard()                  //Will work against Visa, MasterCard, American Express, Discover, Diners Club, and JCB card numbering formats

List of sanitization / filter methods

trim(chars)                     //Trim optional `chars`, default is to trim whitespace (\r\n\t\s)
ltrim(chars)
rtrim(chars)
ifNull(replace)
toFloat()
toInt()
toBoolean()                     //True unless str = '0', 'false', or str.length == 0
toBooleanStrict()               //False unless str = '1' or 'true'
entityDecode()                  //Decode HTML entities
entityEncode()
xss()                           //Remove common XSS attack vectors from text (default)
xss(true)                       //Remove common XSS attack vectors from images

Extending the library

When adding to the Validator prototype, use this.str to access the string and this.error(this.msg || default_msg) when the string is invalid

var Validator = require('validator').Validator;
Validator.prototype.contains = function(str) {
    if (!~this.str.indexOf(str)) {
        this.error(this.msg || this.str + ' does not contain ' + str);
    }
    return this; //Allow method chaining
}

When adding to the Filter (sanitize) prototype, use this.str to access the string and this.modify(new_str) to update it

var Filter = require('filter').Filter;
Filter.prototype.removeNumbers = function() {
    this.modify(this.str.replace(/[0-9]+/g, ''));
    return this.str;
}

Error handling

By default, the validation methods throw an exception when a check fails

try {
    check('abc').notNull().isInt()
} catch (e) {
    console.log(e.message); //Invalid integer
}

To set a custom error message, set the second param of check()

try {
    check('abc', 'Please enter a valid integer').notNull().isInt()
} catch (e) {
    console.log(e.message); //Please enter a valid integer
}

To attach a custom error handler, set the error method of the validator instance

var Validator = require('validator').Validator;
var v = new Validator();
v.error = function(msg) {
    console.log('Fail');
}
v.check('abc').isInt(); //'Fail'

You might want to collect errors instead of throwing each time

Validator.prototype.error = function (msg) {
    this._errors.push(msg);
}

Validator.prototype.getErrors = function () {
    return this._errors;
}

Contributors

• PING - Fixed entity encoding
• Dan VerWeire - Modified the behaviour of the error handler
• ctavan - Added isArray and isUUID()
• foxbunny - Added min(), max(), isAfter(), isBefore(), and improved isDate()
• oris - Addded in()

LICENSE

(MIT License)

Copyright (c) 2010 Chris O'Hara [e-mail]

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.