ember-argument-types

Run-time type checking for arguments passed to an Ember template. The core use-case is components but this addon can also be used to type check models returned from a route or anything else accessible in a template. Under the hood arg-type leverages assert from @ember/debug so no errors will be emitted in production builds.

Compatibility

• Ember.js v3.12 or above
• Ember CLI v2.13 or above
• Node.js v10 or above

Installation

ember install ember-argument-types

Usage

The arg-type helper handles type checking arguments based on the validator passed as the second argument. A validator is a special string or a function which validates an argument. See below for basic and advanced usage.

Basic validation

Basic validation is handled by passing a string as the second argument to the arg-type helper.

{{arg-type @myArg "any"}}
{{arg-type @myArg "boolean"}}
{{arg-type @myArg "function"}}
{{arg-type @myArg "null"}}
{{arg-type @myArg "number"}}
{{arg-type @myArg "object"}}
{{arg-type @myArg "string"}}
{{arg-type @myArg "symbol"}}
{{arg-type @myArg "undefined"}}

Advanced validators

Advanced validation is handled by passing a function as the second argument of the arg-type hepler. Internally the basic validation strings are all converted to validator functions. The signature of the functions is as follows:

interface Validator {
  (value: any): string | undefined;
}

Return undefined to indicate the value is valid. Return a string (reason) to indicate the value is invalid and an error will be thrown with the reason appended to the error output for debugging.

Included helpers

array-of

The array-of hepler is used to validate arrays. It expects a single positional argument of a basic or advanced validator.

{{arg-type @myArg (array-of "string")}}
{{arg-type @myArg (array-of (shape-of firstName="string" lastName="string"))}}

instance-of

The instance-of hepler is used to validate an argument is an instance of a class. it expects a single positional argument of a class.

{{arg-type @myArg (instance-of this.MyClass)}}

optional

The optional hepler is a wrapper around the union-of helper. It expects a single positional argument of a basic or advanced validator and adds null and undefined as valid types.

{{arg-type @myArg (optional "string")}}

one-of

The one-of helper is used to validate an argument against a set of allowed values. It accepts any number of positional arguments it will use strict equality checking to ensure @myArg is one of the provided values.

{{arg-type @myArg (one-of "dark" "light")}}

shape-of

The shape-of helper is used to structurally type check an object. It expects only key word arguments whose keys represent properties in the object and whose values are a basic or advanced validator.

{{arg-type
  @myArg
  (shape-of
    firstName="string"
    lastName="string"
    age="number"
    hobbies=(array-of "string")
  )
}}

union-of

The union-of helper is used to allow an argument to be several types. It expects any number of positional arguments it will use to validate @myArg against.

{{arg-type @myArg (union-of "number" "string")}}

Contributing

See the Contributing guide for details.

License

This project is licensed under the MIT License.