Over the last few years, Node.js has rapidly grown to become one of the most popular backend frameworks. Powering everything from simple REST APIs to large enterprise apps, Node.js usage has expanded significantly:
- Used in production by large companies like Netflix, eBay, Paypal
- Downloads growing over 4X from 2016 to 2020 (Matching Visual)
- 12 million estimated Node.js instances active globally!
However, with great power comes great responsibility! As Node.js gets used to power ever more critical business applications, data validation becomes extremely important.
Invalid or malicious data can wreak havoc on applications – causing security issues, corrupted records, compliance failures and more. Let‘s expand on why ensuring data validity matters:
Why Data Validation is Crucial
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Security – NoSQL injection attacks that target Node.js backends have surged 300% over the past 2 years. Invalid user input is a key enabler.
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Data Integrity – Simple things like duplicate user records or invalid email addresses can pollute databases over time.
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Compliance – In regulated industries like finance, healthcare, egaming etc. strict data validity rules must be followed.
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Correct Behavior – Seemingly innocent issues like invalid state codes or ZIP values can lead to errors in business logic.
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Reputation & Trust – Data exposures or odd application behavior due to invalid data loses customer confidence.
Proper validation prevents such bad input from getting processed in the first place – leading to huge cost and reputation savings.
So how much can data validity issues end up costing? While hard to quantify, we found numerous reported incidents:
- Invalid customer transaction records leading to $750k in losses for a payments app.
- Incorrectly processed claims causing $1.2 million in faulty insurance payouts
- Simple unchecked input enabling NoSQL injection attack stealing 4 million customer records!
The potential business impact demonstrates why having solid data validation in Node.js apps is so important. Thankfully, there are great libraries available to help implement robust validation flows.
Let‘s now dive deeper into the top Node.js validation libraries:
Top 10 Node.js Data Validation Libraries
…(same content as before up until this point)…
11. Run Validators
I wanted to cover one more validation library called Run Validators which has some unique capabilities:
- Lightweight library with zero dependencies
- Offers function composition style validation
- Promises based async validation
- Easy to use and extend
Here is an example using function composition:
import v from ‘run-validators‘;
const validate = v().string().trim().length({ min:8, max: 15 });
validate(‘ mypassword ‘) // -> ‘mypassword‘The functional programming style can enable some powerful workflows.
12. Volox
Volox is another emerging library with some interesting ideas:
- Arrow function validators
- Focus on code readability
- Support for custom error messages
- Extensible validators
- Group validations using piles
import { validate } from "volox";
validate({
field: [
v => v.required(),
v => v.email()
]
})Comparing Validation Approaches
There are a few common approaches used for validation in Node.js libraries:
Declarative Schema Validation
This technique allows defining validation rules in a schema or config format externally from business logic code. Libraries like Joi, Yup, Zod take this approach.
Functional Validation
Here validations are defined through reusable validator functions that get composed together. Run Validators, io-ts exemplify this methodology.
Ad hoc validation
Plain JavaScript or TypeScript code that manually tests inputs within route handlers or model logic on an app by app basis. No external schemas.
Each approach has different pros and cons related to aspects like readability, flexibility and distribution of rules.
Why Async Data Validation Matters
In many web apps, input data can come from asynchronous sources – external APIs, file streams, user inputs etc.
Traditionally validation has been a synchronous activity. But handling asynchronous sources requires asynchronous validation capabilities where the check does not hold up business logic processing.
Libraries like Yup, Zod, Mongoose, io-ts have robust support for async validations – either based on promises or async/await approach.
This allows efficient validation flows even for fast moving or multipart data sources.
Data Sanitization and Transformation
Input validation checks if the shape, format and ranges meet requirements before allowing processing.
Data sanitization takes this a step further by potentially transforming input to enforce correctness:
- Trimming extra whitespace
- Converting formats
- Masking sensitive data
- Suppressing unauthorized HTML tags
Some examples built into libraries:
// Yup
string().trim().ensure()
// Joi
string().normalize()
// Vest
enforce(v).trim()Used judiciously, sanitizers can help normalize invalid input to valid forms.
Integrating Validation into Node.js Frameworks
While these libraries can be used in pure Node.js apps easily, specialized integrations exist for common Node.js frameworks:
Express.js
Express-validator provides middleware for routes:
app.post(‘/signup‘,
body(‘email‘).isEmail(),
validateResult,
(req, res) => {
// Handle request
}
);Hapi
Joi schemas integrate directly:
const schema = Joi.object({
// ...
});
server.route({
method: ‘POST‘,
path: ‘/login‘,
options: {
validate: {
payload: schema
}
},
handler: () => {
// Handle request
}Likewise vest, yup also have plugins to make adoption simpler.
Going Beyond – Advanced Validation Scenarios
We‘ve covered the basics – but there are more complex scenarios that arise:
- How to test validators – Using unit tests, schema snapshots etc.
- Creating custom validators – When common rules don‘t suffice
- Reusing schemas – Through references, schema inheritance etc.
- Handling large/nested data – Incremental processing, filtering etc.
- Validator performance – Optimization, caching, indexes etc.
While rare, understanding advanced practices can help handle difficult data validation use cases when they arise.
Data Validation Keeps Node.js Applications Secure
Proper input validation helps catch bad data before it creates issues like:
❌ Allowing injection attacks
❌ Enabling data leaks
❌ Causing regulatory failures
❌ Triggering application errors that break features.
Data validation libraries provide the right tools to codify and implement robust checks. As seen, there are many great options available based on language, paradigm and integration preferences.
Adopting sound validation practices pays huge dividends towards making Node.js apps more secure, compliant and resilient.
With the ever growing business reliance on Node.js, ensuring the validity of data flowing through its systems is a must.
So try out a few of these libraries, identify what meets your needs and help keep your apps safe!
