Typist


Type check function return values at run time, or type check any value any time.

1. Install
1. All In One Example
1. Return Values
1. Any Value

Install

``
npm install typist.js --save
`

All in one example

Seamlessly type check the return type as well as input types for the life of the function.

`js
var makeArray = type.takes(Array, String, Number)
.does(function(input, foo, bar) {
input.push(foo, bar);
return input;
})
.returns(Array)
.done();

makeArray([], "1", 2); // ["1", 2]
makeArray([], 1, 2); // Throws TypistError
`

Or you can use the features separately but all together for the same effect.

`js
var type = require("typist");

var makeArray = type(Array, function(input, foo, bar) {
type.checks([Array, input], [String, foo], [Number, bar]);
input.push(foo, bar);
return input;
});

makeArray([], 1, 2); // throws TypistError
makeArray([], "1", 2); // ["1", 2]
`

Return Values

Typist creates a curried function of your type and will check against that type any time a value is returned from it. Ensure your function will always return what you expect it to.

`js
var type = require("typist");

var makeArray = type(Array, function(input) {
return input.push("Foo");
});

makeArray("string"); // throws TypistError
makeArray([]); // ["Foo"]
`

Any Value

Type check any value any time

`js
var type = require("typist");

type.is.array(["Foo"]); // true
type.is.string(["Bar"]); // false

type.array(["Foo"]); // ["Foo"]
type.array("Bar"); // throws TypistError
`

You can also type check many values, which is useful for checking all your function arguments at the top of the function.

`js
var type = require("typist");

var makeArray = function(input, foo, bar) {
type.checks([Array, input], [String, foo], [Number, bar]);
input.push(foo, bar);
return input;
});

makeArray([], 1, 2); // throws TypistError
makeArray([], "1", 2); // ["1", 2]
`

Currently Supporting

I'm adding more types as I have time, but currently have:

- Object
- Array
- String
- Number
- Function
- Boolean
- Date
- RegEpx
- Error

Testing

You will need to install grunt-cli if you haven't already.
Run grunt test to run tests and coverage. Coverage is saved in coverage` folder.