# Dynamically Loading Native Modules in Synchronous Mode

The **loadNativeModule** API is used to dynamically load native modules in synchronous mode. It is used to load native modules only when needed, preventing unnecessary modules from being loaded during application startup. However, using this API incurs a delay due to the loading of the .so file, and therefore you need to assess whether this will impact functionality.

## API Description

```js
loadNativeModule(moduleName: string): Object;
```

| Parameter           | Description         |
| :------------- | :----------------------------- |
| moduleName            | Name of the module to load.      |

> **NOTE**
>
> The name of the module loaded by **loadNativeModule** is the name provided in **dependencies** in the **oh-package.json5** file of the dependency.
>
> **loadNativeModule** can be used only to load modules in the UI main thread.
>
> Dependencies must be configured for the API call regardless of whether the parameter is a constant string or variable expression.

## Supported Scenarios

| Scenario           | Example          | 
| :------------- | :----------------------------- | 
| System library module       | Load **@ohos.** or **@system.**.       | 
| Native module in an application| Load **libNativeLibrary.so**.|

## Usage Example

- **Loading a system library module to a HAP**

  ```js
  let hilog: ESObject = loadNativeModule("@ohos.hilog");
  hilog.info(0, "testTag", "loadNativeModule ohos.hilog success");
  ```

- **Loading a native library to a HAP**

  The **index.d.ts** file of **libentry.so** is as follows:

  ```javascript
  //index.d.ts
  export const add: (a: number, b: number) => number;
  ```

1. When loading a local .so library, configure dependencies in the **oh-package.json5** file.

   ```json
   {
       "dependencies": {
           "libentry.so": "file:../src/main/cpp/types/libentry"
       }
   }
   ```

2. Configure the **build-profile.json5** file.

   ```json
   {
       "buildOption" : {
           "arkOptions" : {
               "runtimeOnly" : {
                   "packages": [
                       "libentry.so"
                   ]
               }
           }
       }
   }
   ```

3. Use **loadNativeModule** to load **libentry.so** and call the **add** function.

   ```js
   let module: ESObject = loadNativeModule("libentry.so");
   let sum: number = module.add(1, 2);
   ```