> For the complete documentation index, see [llms.txt](https://jsf.gitbook.io/jsf/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://jsf.gitbook.io/jsf/schema/intro.md).

# Intro to Schema

The schema contains JSF props, that together form a model definition of document. Because JSF is written in JSON format, it supports all JSON types and some extra. Each prop can define the following properties:

* Type (string, number, array, object, ...).
* Validation rules.
* Enabled conditions.
* If it's array or object type children props.
* Handler.

{% hint style="info" %}
Exported TypeScript type **JsfPropTypes** describes all possible prop types. **JsfProp** type describes all possible prop definitions. **JsfPropValue** type describes all possible values that props can return.
{% endhint %}

In order to check what type is prop you can use one of the following functions:

* **isPropNull** check if prop type is **null**.
* **isPropObject** check if prop type is **object**.
* **isPropArray** check if prop type is **array**.
* **isPropString** check if prop type is **string**.
* **isPropNumber** check if prop type is **number**.
* **isPropInteger** check if prop type is **integer**.
* **isPropBoolean** check if prop type is **boolean**.
* **isPropBinary** check if prop type is **binary**.
* **isPropId** check if prop type is **ID** compatible with Mongo Object ID.
* **isPropRef** check if prop type is **reference**.
* **isPropDate** check if prop type is **date**.

Schema property is required and it must contain one of props. Usually, first level (root) prop is object.

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