Superschema

A simple tool for checking JS types and object formats.

Types

The currently supported types are boolean, number, string, array, function, object, date, and also the knockout observable.

Usage

After requiring the superschema module, you can use the superschema.check(data, pattern, name) function. Here data is the data you want to typecheck, pattern defines the type pattern your data should conform to. The check function will throw an error if the data doesn't correspond to the given type, and will use name in the error message to make it more informative (it defaults to 'configObject' if name is not given).

Pattern syntax

• Simple object structure: E.g. if your data should be an object with username, id, registeredAt properties, where username is a string, id is a number and registeredAt is a JS Date object, you can check that using the following pattern:

{
	username: "string",
	id: "number",
	registeredAt: "date"
}

• Nested objects: you can type in deeper object hierarchies as they are, e.g.

{
	id: "number",
	userData: {
		username: "string",
		userid: "number",
		purchases: "array"
	},
	productData: {
		productId: "number",
		description: "string"
	}
}

means that the userData and productData properties should be objects with the given substructures.

• Arrays: if you want to check the type of elements in an array, you can use the

{
	purchases: {
		__type: "array",
		__elements: {
			time: "date",
			id: "number"
		}
	}
}

syntax - this means that the purchase prop has to be an array, and its elements should be objects with time and id properties. Or if your array element doesn't have to have some predefined substructure, you can use the "array number" and similar type definitions - it means that the array should have number-type elements.

• Non-mandatory and nullable properties: If a property is allowed to be null or undefined, you can use a "nullable number" or "optional number" (or even "nullable optional number") type syntax. In case of objects and arrays you can use the __nullable and __required properties, e.g:

{
	userdata: {
		__required: false,
		purchases: {
			__type: "array",
			__nullable: true
		}
	}
}

means that userdata, if not undefined, should be an object with a purchases property, which can be null or an array.

• Enums: If a property can only have one of a collection of given values, you give the allowed values in an array in the __allowedValues property:

{
	userdata: {
		rank: {
			__allowedValues: ["basic", "vip", "superhero"]
		}
	}
}

• KnockoutJS observables: To check knockout observable types, you should call the superschema.extend({ knockout: yourKnockoutInstance}) function - here of course yourKnockoutInstance should be the knockout instance used in your code. (This is because superschema uses ko's own isObservable function for typechecking). You have to call this only once in your code. After that, you can use the "observable" type, e.g. the pattern

{
	username: "observable",
	id: "observable number",
	lastOrder: {
		__type: "observable",
		__value: {
			id: "number",
			description: "string"
		}
	}
}

means username should be an observable, id should be an observable containing a number, and lastOrder should be an observable containing an object with id, description properties.

Error message format

The error message will indicate the first place where the data doesn't conform to the given pattern (e.g. something like config.userdata.id should have number type or userdata.purchases[1].date has to be a date object!), or the first place when an unknown type was encountered in the pattern (to protect from misspellings). So e.g. if you type fuction as type somewhere, the error message will be Unknown type: fuction.