## Import / Export (In-Memory)

> Persistent-Indexes and Worker-Indexes don't support Import/Export.

Export an `Index` or `Document-Index` to the folder `/export/`:

```js
import { promises as fs } from "fs";

await index.export(async function(key, data){
  await fs.writeFile("./export/" + key, data, "utf8");
});
```

Import from folder `/export/` into an `Index` or `Document-Index`:

```js
const index = new Index({/* keep old config and place it here */});

const files = await fs.readdir("./export/");
for(let i = 0; i < files.length; i++){
  const data = await fs.readFile("./export/" + files[i], "utf8");
  await index.import(files[i], data);
}
```

> You'll need to use the same configuration as you used before the export. Any changes on the configuration needs to be re-indexed.

## Fast-Boot Serialization for Server-Side-Rendering (PHP, Python, Ruby, Rust, Java, Go, Node.js, ...)

> This is an experimental feature with limited support which probably might drop in future release. You're welcome to give some feedback.

When using Server-Side-Rendering you can create a different export which instantly boot up. Especially when using Server-side rendered content, this could help to restore a __<u>static</u>__ index on page load. Document-Indexes aren't supported yet for this method.

> When your index is too large you should use the default export/import mechanism.

As the first step populate the FlexSearch index with your contents.

You have two options:

### 1. Create a function as string

```js
const fn_string = index.serialize();
```

The contents of `fn_string` is a valid Javascript-Function declared as `inject(index)`. Store it or place this somewhere in your code.

This function basically looks like:

```js
function inject(index){
    index.reg = new Set([/* ... */]);
    index.map = new Map([/* ... */]);
    index.ctx = new Map([/* ... */]);
}
```

You can save this function by e.g. `fs.writeFileSync("inject.js", fn_string);` or place it as string in your SSR-generated markup.

After creating the index on client side just call the inject method like:

```js
const index = new Index({/* use same configuration! */});
inject(index);
```

That's it.

> You'll need to use the same configuration as you used before the export. Any changes on the configuration needs to be re-indexed.

### 2. Create just a function body as string

Alternatively you can use lazy function declaration by passing `false` to the serialize function:

```js
const fn_body = index.serialize(false);
```

You will get just the function body which looks like:

```js
index.reg = new Set([/* ... */]);
index.map = new Map([/* ... */]);
index.ctx = new Map([/* ... */]);
```

Now you can place this in your code directly (name your index as `index`), or you can also create an inject function from it, e.g.:

```js
const inject = new Function("index", fn_body);
```

This function is callable like the above example:

```js
const index = new Index();
inject(index);
```