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## Resource: Call Backend Code from a jsw Web Module

## Article: Call Backend Code from a jsw Web Module

## Article Link: https://dev.wix.com/docs/develop-websites/articles/coding-with-velo/backend-code/web-modules/call-backend-code-from-a-jsw-web-module.md

## Article Content:

# Deprecated: Call Backend Code from the Frontend Using a jsw Web Module

[Web modules](https://dev.wix.com/docs/develop-websites/articles/coding-with-velo/backend-code/web-modules/about-web-modules.md) allow you to write backend functions that you can easily call from the frontend.

<blockquote class="warning">

**Warning:** 
Web modules defined using `.jsw` files are deprecated and you will soon be unable to create new `.jsw` files. However, existing `.jsw` web modules will continue work as expected. Switch to [web module defined using `.web.js` files](https://dev.wix.com/docs/develop-websites/articles/coding-with-velo/backend-code/web-modules/call-backend-code-from-the-frontend.md) for your current and future projects.

</blockquote>

The following describes how to create, export, and call web module functions.


## Step 1 | Define a function in the backend

Add an exported function to an existing `.jsw` file.

  ```js
  export myFunction(someParam) {
    // Some functionality to call from the frontend
    return `You passed me ${someParam}`;
  }
  ```

## Step 2 | Set permissions
 Set [permissions](https://dev.wix.com/docs/develop-websites/articles/coding-with-velo/backend-code/web-modules/about-web-modules.md#permissions) for each function in the web module if necessary. The default permission is **Anyone**.

You can set permissions in the Wix Editor or by editing the permissions.json file, depending on your development environment:

::::tabs

:::Wix-Editor

To set permissions for a web module function:

1. Hover over your web module, click the more actions menu, and select **Edit Web Module Permissions**. \
The web module permissions panel opens and displays each exported function in your web module.
    
1. Click the dropdown next to a function name to define its permissions.

:::

:::Wix-and-Local-IDE

When using the Wix IDE or a local IDE with GitHub integration, you can add and edit permissions using the `permissions.json` file.

 The `permissions.json` file is located in the `src/backend` folder. The file contains a `"web-methods"` object where each key represents a web module file using the syntax `backend/{path-to-file}/<file-name>.jsw`. Under each file key, you define permission objects for each exported function. 

 The `"web-methods"` object must also contain a `"*"` key that defines default permissions for any functions not explicitly configured.

 Set permissions using the following values:

* **Owner-only access**: 
  * `siteOwner.invoke`: `true`
  * `siteMember.invoke`: `false`
  * `anonymous.invoke` : `false`
* **Site member access**: 
  * `siteOwner.invoke`: `true`
  * `siteMember.invoke`: `true`
  * `anonymous.invoke` : `false`
* **Anyone can access**:
  * `siteOwner.invoke`: `true`
  * `siteMember.invoke` : `true`
  * `anonymous.invoke`: `true`


Here is an example with 3 functions from `helperFunctions.jsw`, each having different permission levels:

```json
// permissions.json file
{
  "web-methods": { 
    // Default web method.
    "*": {
      "*": {
        "siteOwner": {
          "invoke": true
        },
        "siteMember": {
          "invoke": true
        },
        "anonymous": {
          "invoke": true
        }
      }
    },
    // Web method for the web module. 
    "backend/helperFunctions.jsw": {
      "calculate": {
        "siteOwner": {
          "invoke": true
        },
        "siteMember": {
          "invoke": true
        },
        "anonymous": {
          "invoke": true
        }
      },
      "fetchData": {
        "siteOwner": {
          "invoke": true
        },
        "siteMember": {
          "invoke": false
        },
        "anonymous": {
          "invoke": false
        }
      },
      "syncWithServer": {
        "siteOwner": {
          "invoke": true
        },
        "siteMember": {
          "invoke": true
        },
        "anonymous": {
          "invoke": false
        }
      }
    }
  }
}
```

:::
::::


## Step 3 | Call the function in the frontend

To call a web method from the frontend:

1. Import the exported web method from the web module you created above:

    ```javascript
    import { myFunction } from 'backend/weather.web'; 
    ```

2. Call the imported function:

    ```js
    const fromBackend = await myFunction(someValue);
    ```

    Remember, web module functions are always asynchronous.