Straints can be installed through npm.

To add straints to your project via npm do

$ npm install straints --save

To use in the browser link in one of the js files.

<script src=".../straints.min.js"></script>

Alternatively, you can use the unpkg CDN.

<script src=""></script>

Once you've got the script in your page, you can do

    var instance = straints({ /* config options */ });

Configuration Options

Here's a list of the available configuration options.

  • validator (object)
    Specify the test method implementation(s) to use here. (As of v0.7.0 straints no longer comes with a default validator method implementation)

  • schema (object)
    Validation schema definition for the straints instance.

  • contexts (object)
    Default validation context(s) to use if none passed to the straints instance.

  • levels (string|array)
    Additional validation levels can be specified here with an array or comma-delimited string.


As far as straints is concerned, a validator is simply an object with validation methods (or test methods).

var instance = straints({ validator: myTestMethods });
// OR, if using multiple validator libraries
var instance = straints({ validator: { alyze: alyze.create(), myTestMethods } });

In the validation schema a reference to a test method is its full dot-notated path.

Validation Methods

Straints expects test methods to be defined in the following way:

function testMethod(value: any, ...args: any[]): boolean|Function|Promise

The test method must accept the test value as the first argument and may also accept or require additional arguments.

Straints handles the test method return value as follows:

  • a Promise its .then() is called with success and error callbacks
  • a function it is called with success and error callbacks
  • a boolean then it is handled as a successful validation

If the value returned is none of the above or if the error callback is used then the validation session will be terminated.