Taser


A poor man's static typing.

Write better code, by being more strict with the types and values you expect in
a function. Taser helps you check your input types and values and throws an
error when they are not the expected values.

With taser, you can declare what your expectations are for your inputs and
taser will throw an error whenever the input data doesn't meet your
expectations. For example, if you have a function that multiplies two numbers
together, you can declare your expectations with taser and write your
function without any type checking.

``
var multiply = function (a, b) {
// An error will be thrown if these variables are not numbers
taser('number', a);
taser('number', b);
// Because these are numbers, we can guarantee that this
// function works as expected
return a * b;
};
`

Examples

$3

You can check a value for a specific type.

`javascript
var sayHello = function (str) {
taser(['string'], str);
return 'Hello ' + str + '!';
};
sayHello('Jorge'); // Hello Jorge!
sayHello('Carlos'); // Hello Carlos!
sayHello(57); // Throws an error
sayHello(); // Throws an error
`

$3

You can check a value for multiple types, if your function can take more than one type.

`javascript
var loopThrouhValies = function (arrayOrObject, callback) {
taser(['array', 'object'], arrayOrObject);
taser(['function'], callback);
if (Array.isArray(arrayOrObject)) {
arrayOrObject.forEach(callback);
} else {
for (var key in arrayOrObject) {
callback(arrayOrObject[key], key, arrayOrObject);
}
}
};
sayHello([1, 2, 3], console.log); // [1, 2, 3]
sayHello({ a: 1, b: 2, c: 3 }, console.log); // { a: 1, b: 2, c: 3 }
sayHello(57, console.log); // Throws an error
sayHello("wow", console.log); // Throws an error
`

$3

You can check for types and values, passing an array of valid values.

`
var logNumberBetweeOneAndFive = function (num) {
taser({
type: 'number',
values: [1, 2, 3, 4, 5]
}, num);
console.log('Number:', num);
};
logNumberBetweenOneAndFive(1); // 1
logNumberBetweenOneAndFive(4); // 4
logNumberBetweenOneAndFive(7); // Throws an error
logNumberBetweenOneAndFive('3'); // Throws an error
`

Interfaces

When declaring your checks in your function, often times you want to declare
more complex dependencies. You might want to declare that an object would have
certain properties of a certain type. You can do this with interfaces. After
declaring your interfaces, you can pass those along to taser.

`
var taser = require('taser');
var userInterface = new taser.Interface({
'first_name': taser('string'),
'last_name': taser('string'),
'age': taser('number'),
'email': taser('string')
});

// Will validate and return true
taser(userInterface, {
first_name: 'jorge',
last_name: 'silva',
age: 25,
email: 'jorge.silva@thejsj.com'
});

// Will throw an error
taser(userInterface, {
first_name: 'jorge',
last_name: 'silva',
age: '25', // This is a String, not a number!
email: 'jorge.silva@thejsj.com'
});
`

You can also pass

Types

| name | Examples | Notes |
|-------------|--------------------------------------------|--------------------------------------------------------------------------------------------------------------|
| 'string' | 'hello', 'goodbye', '1' | |
| 'number' | 1, 2, 234.23423, -0.001 | |
| 'boolean' | true, false | |
| 'array' | [1, 2, 3], [{ hello: 'hello' }, 3, "adsf"] | |
| 'object' | { hello: 'hello' }, { name: 'jorge' } | 'object' does not map directly to a JavaScript object. Arrays and null are not considered objects, by taser. |
| 'function' | function (a, b) { return a + b } | |
| 'null' | null | |
| 'undefined' | undefined | |

Currying

If you only pass one argument to the main curry function, taser will return
another function that validates a variable using that parameter.

`
var isString = taser('string');
isString('hello'); // true
isString(1); // Throws Error
`
`
var isAOrB = taser({ type: 'string', values: ['a', 'b' ]});
isAOrB('a'); // true
isAOrB('c'); // Throws Error
`

Legacy / No Currying

In v0.0.1, the value to be checked came first, followed by assertion
declaration (string, array, or object). If you wish to use the function in that
order, include taser as follows:

`
var taser = require('taser').noCurrying;
taser('hello', 'string');
``

This will also disable currying.