arg-check

arg-check is a lightweight library to help developers catch bugs before they skitter in by making sure the right types of arguments are being passed into functions and methods.

It takes two arguments: (1) an argument you've passed into a function declaration, and (2) the type you expect that argument to be. It couldn't be easier:

let argCheck = require('arg-check');

let add = (a, b) => {
  argCheck(a, 'number');
  argCheck(b, 'number');

  return a + b;
};

add(3, 4); // 7

add(3, 'four'); // TypeError: Expected argument to be of type "number" but instead received type "string"

Getting Started

Step 1

In the terminal:

$ npm install arg-check

Step 2

In path/to/my/rad/app/or/whatever/app.js:

let argCheck = require('arg-check');

Step 3

Really, that's it. Start arg-checking!

Supported Argument Types

Note all argument types are lowercase strings.

• 'null'
• 'undefined'
• 'string'
• 'number'
• 'boolean'
• 'array'
• 'object'

argCheck also supports custom class types:

class Person {
  constructor(attributes) {
    this.name = attributes.name;
  }
}

let rachael = new Person({ name: 'Rachael' });

let personName = (person) => {
  argCheck(person, 'person');

  return person.name;
};

personName(rachael); // 'Rachael'
personName({ name: 'Rachael' }) // TypeError: Expected argument to be of type "person" but instead received type "object"

Note again that the expected class name will be a lowercase string.

Contributing

We'd love contributors and feedback! We are currently at 100% test coverage and that's the way we like it. Hit us up and let's make this thing even better.

License

arg-check is released under the MIT License