Typist

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

1. Install
2. All In One Example
3. Return Values
4. 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.

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.

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.

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

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.

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.