# Accessor

Source code is hosted on [GitHub](https://github.com/corets/accessor)

This library allows you to create a statically typed object accessor based on the [Proxy API](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Proxy). The main purpose of this package is to allow dynamic object access in a static manner, without having to rely on dynamic, string based keys. Code won't compile if you try to access a path that does not exist. You keep control over what is returned from the getter, by providing a custom access handler.

{% tabs %}
{% tab title="yarn" %}

```bash
yarn add @corets/accessor
```

{% endtab %}

{% tab title="npm" %}

```bash
npm install --save @corets/accessor
```

{% endtab %}
{% endtabs %}

## createAccessor() <a href="#createaccessor" id="createaccessor"></a>

Create an accessor instance of the type `ObjectAccessor`.

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })
```

Now you can statically access every object field:

```typescript
accessor.some.field.get()
```

You can provide a custom access handler to customise the access behaviour. Below is an example of how one could statically access translations, proxied by a translation library, using the accessor.

```typescript
import { createAccessor } from "@corets/accessor"

const translations = {  
    pages: {    
        home: {      
            title: "Home {replacement}"    
        },    
        about: {      
            title: "About {replacement}"    
        }  
    }
}

const translator = createSomeSortOfTranslator(translations)

const locales = createAccessor(translations, (source, key, ...replacements: any[]): string => {  
    return translator.get(key, { replacements })
})
```

Now you can indirectly access translations through the accessor, without using any dynamic keys.

```typescript
const translatedHomePageTitle = locales.pages.home.title.get("Page")
```

{% hint style="info" %}
Trying to access a missing key will result in a compilation error. 💥
{% endhint %}

This library is used internally by this translation library, to power its static translations access:

{% content-ref url="/pages/-MeeFAgcZV96KXm0W1WU" %}
[Translator](/services/translator.md)
{% endcontent-ref %}

## ObjectAccessor.key() <a href="#objectaccessorkey" id="objectaccessorkey"></a>

Get absolute field key:

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })

accessor.some.field.key()
```

## ObjectAccessor.keyAt() <a href="#objectaccessorkeyat" id="objectaccessorkeyat"></a>

Get absolute field key, bypassing the static typing:

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })

accessor.some.keyAt("field")
```

## ObjectAccessor.get() <a href="#objectaccessorget" id="objectaccessorget"></a>

Get field value coming from the access handler:

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })

accessor.some.field.get()
```

## ObjectAccessor.getAt() <a href="#objectaccessorgetat" id="objectaccessorgetat"></a>

Get field value coming from the access handler, bypassing the static typing:

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })

accessor.some.getAt("field")
```

## ObjectAccessor.has() <a href="#objectaccessorhas" id="objectaccessorhas"></a>

Check if a field exists:

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })

accessor.some.field.has()
```

## ObjectAccessor.hasAt() <a href="#objectaccessorhasat" id="objectaccessorhasat"></a>

Check if a field exists, bypassing the static typing:

```typescript
import { createAccessor } from "@corets/accessor"

const accessor = createAccessor({ some: { field: "value" } })

accessor.some.hasAt("field")
```


---

# Agent Instructions: Querying This Documentation

If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question.

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

```
GET https://docs.corets.io/services/accessor.md?ask=<question>
```

The question should be specific, self-contained, and written in natural language.
The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.