Note from 2021: Just use TypeScript lol

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Installation

npm install typesjs   # Node
bower install typesjs # Browser

What can TypesJS do for me?

var t = require('typesjs');

t("String", String);
t(23, Number);
t([], Array);

t([], String); // Throws a TypeError.

If you need a variable to be a String, for example, typesjs can halt your code safely when it's not.

What if I dislike errors?

t.check('Lorem', String); // Returns true.
t.check(1999, String);    // Returns false.

check will return a boolean based on the match.

What if I do like errors?

try {
    t([], String);
} catch(e) {
    // ...
}

try/catch blocks are your friend here.

What if I make my own types?

function Message(text) {
	this.text = text;
}
var message = new Message('Lorem');
t(message, Message);

Custom types are fully supported.

What if a value is null or undefined?

t(undefined, String); // Throws a TypeError.

What if a value isn't required though?

t(undefined, String, false); // Returns true.

Just pass false or "optional" as the third parameter. This will allow for null and undefined values.

t(undefined, String, "optional"); // Returns true.

Passing "optional" is more verbose, but perhaps more readable.

What if I want to allow multiple types?

t("23", [Number, String]);

Just pass an array of types.

What if I want to disable typesjs, during runtime?

t.enabled = false;

When disabled, typesjs will always return true.

Note: This changes the global setting for all the code using TypesJS. Only use this in applications and never in libraries.

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Feel free to make a GitHub issue, or pull request. Thanks.