The aproba package is a lightweight argument validation library for Node.js. It allows developers to assert types and values of arguments in functions, ensuring that the functions are called with the expected arguments. This can help catch bugs early in the development process by providing a simple and concise way to validate function inputs.

What are aproba's main functionalities?

Type validation

This feature allows you to validate the types of arguments passed to a function. In the code sample, 'N' stands for number and 'S' for string, ensuring the first argument is a string and the second is a number.

"use strict";
const A = require('aproba');

function exampleFunction(a, b) {
  A('NS', arguments);
  // Function logic here
}

exampleFunction('hello', 123);

Optional arguments

aproba supports optional arguments in its type validation. In the example, the '?' after 'S' indicates that the second argument is optional. This means the function can be called with just the first argument.

"use strict";
const A = require('aproba');

function exampleFunction(a, b) {
  A('NS?', arguments);
  // Function logic here
}

exampleFunction('hello');

Other packages similar to aproba

Readme

Source

aproba

A rediculously light-weight function argument validator

var validate = require("aproba")

function myfunc(a, b, c) {
  // `a` must be a string, `b` a number, `c` a function
  validate('SNF', arguments) // [a,b,c] is also valid
}

myfunc('test', 23, function () {}) // ok
myfunc(123, 23, function () {}) // type error
myfunc('test', 23) // missing arg error
myfunc('test', 23, function () {}, true) // too many args error

Valid types are:

type	description

| matches any type A | instanceof Array OR an arguments object S | typeof == string N | typeof == number F | typeof == function O | typeof == object and not type A and not type E B | typeof == boolean E | instanceof Error OR null

Validation failures throw one of three exception types, distinguished by a code property of EMISSINGARG, EINVALIDTYPE or ETOOMANYARGS.

If an error argument is found and is not null then the remaining arguments will not be validated.

Why this exists

I wanted a very simple argument validator. It needed to do two things:

Be more concise and easier to use than assertions
Not encourage an infinite bikeshed of DSLs

This is why types are specified by a single character and there's no such thing as an optional argument.

This is not intended to validate user data. This is specifically about asserting the interface of your functions.

If you need greater validation, I encourage you to write them by hand or look elsewhere.

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Last updated on 09 Apr 2015

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