proving

A very simple type checking helper.

Table of Contents

1. Overiew
2. Installation
3. Usage
4. APIs

1. Overview

When I was doing many type checking for function arguments, I found myself doing a lot of if (type_not_met) throw new TypeError(msg) to make assertions. That's why I collect all these simple checkers together to be DON'T REPEAT YOURSELF as well as to help myself lower down line-of-codes.

Only 56 LOC to meet my daily use.

2. Installation

$ npm install proving --save

3. Usage

Here is a quick example, it's very very simple.

var proving = require('proving');
function myFunc(foo, bar) {
    proving.number(foo, 'foo should be a number.');
    proving.string(bar);    // this will throw will a default message
    // ...
}

myFunc(20, 'hello');    // not throw

myFunc('x', 'hello');   // throw TypeError('foo should be a number.')

myFunc(20, {});         // throw TypeError('Input value should be a string.')

4. APIs

.defined(val[, msg])

Throw if val is undefined.
Default message: 'Input value should be given.'

.string(val[, msg])

Throw if val is not a string.
Default message: 'Input value should be a string.'

.number(val[, msg])

Throw if val is not a number. Also throw if val is NaN.
Default message: 'Input value should be a number and cannot be a NaN.'

.boolean(val[, msg])

Throw if val is not a bool.
Default message: 'Input value should be a bool.'

.array(val[, msg])

Throw if val is not an array.
Default message: 'Input value should be an array.'

.object(val[, msg])

Throw if val is not an object. Also throw if val is NaN or null.
Default message: 'Input value should be an object.'

.fn(val[, msg])

Throw if val is not a function.
Default message: 'Input value should be a function.'

.stringOrNumber(val[, msg])

Throw if val is not a string nor a number.
Default message: 'Input value should be a number or a string.'