Simple Javascript Modules - Local Storage Module
Tags: todayilearned, javascript, webdev, beginners
Published: 2021-06-26 13:50:40

Working as a web developer I work on the client side dealing with lots of continuous data from the server. All though it is a good practice to not store data on the client side, there will be many cases where we want to store some information on the client for faster access. A good use case would be the app theme `theme: "light"` or `theme: "dark"`.

So that is where we can use Local Storage of the Browser using the `window.localStorage API`. It is a free storage space available for almost all major browsers and we can save a considerable amount of safe data for quick use in our application. It can be found on almost all major browsers. You can view, modify or delete the local storage data under the Application Tab in your browser followed by Local Storage and clicking your domain.

![Local Storage Description](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/advorhz4c96b4nvl3qb5.png)

As you can see here in the code below, I have added all the things that we mostly do with local storage. Usually all these functions are separately written in a utility module. But here I have kept it separately so that in any case of change, we just replace the functions inside the module and our application code remains untouched. `The whole point of writing these functions together as a module is to keep the code clean, crisp and understandable.`

```javascript
// A localStorage object for performing crud operations on window.localStorage with ease

const Storage = {
  // check if local storage is supported on browser
  exists: (window.localStorage !== undefined),
  // get the local storage data of the key
  get(key) {
    if (!this.exists) return;
    const data = window.localStorage.getItem(key);
    if (!data) return;
    return JSON.parse(data);
  },
  // add a new data to given key in local storage
  add(key, data) {
    if (!this.exists) return;
    window.localStorage.setItem(key, JSON.stringify(data));
  },
  // remove the data by the given key from local storage
  remove(key) {
    if (!this.exists) return;
    window.localStorage.removeItem(key);
  },
  // wipe entire local storage of current domain
  wipe() {
    if (!this.exists) return;
    window.localStorage.clear();
  }
}

export default Storage;
```

I have written a total of 5 properties on my module here which will use the `window.localStorage API` and are as follows.

1.`exists` - This contains a boolean value that checks if the current browser supports local storage or not.

2.`get(key)` - This function is used to get the data that is associated with the key that is sent in the parameters. For example if `get("name")` will get you the data that is saved under the name key in local storage. This function calls the window function called `localStorage.getItem()` which takes 1 parameter "key".

3.`add(key, data)` - This function is used to add new data to the local storage. The `key` attribute specifies to which key the data should be added to and the `data` attribute contains the data to be added. This function calls the window function called `localStorage.setItem()` which takes 2 parameters "key" and "data". It could be anything like a string, number, array, object etc.

For example running this => ```javascript
Storage.add("myKey", { name: "Sooraj" })
```
Will add this under the key called "myKey"
![Added Local Storage](https://dev-to-uploads.s3.amazonaws.com/uploads/articles/6r9tubucxgkzrgtjjaxv.png)

4.`remove(key)` - This function is used to remove the data associated with the key that is sent in the parameters. This function calls the window function called `localStorage.removeItem()` which takes 1 parameter "key". If `remove("myKey")` is called the data that was added before would be cleared from the storage.

5.`wipe()` - This is a method I would not use that many times. This function calls the window function called `localStorage.clear()` which takes no parameters. This function clears all the local storage data associated with the client on that domain.

Well, this is my Storage module. Hope you guys found it useful. Go ahead and try it out...