JS Terminal

This project is based on 2 main objects which allow me to work in a very easy way with the terminal and all the file structure.

CLI

As we are working on the implementation of a terminal which allows to execute commands, I thought of creating an object which would provide me with all the basic functionalities expected from such a terminal like executing a command, checking if a command exists, printing results in the terminal etc.

For the implementation of each command, I created an object which contains as keys the names of each command and as value all the information about that command including a run function to execute it.

This way, to execute any command entered by the user I only need to:

    cli.run(command, params);

And the object cli will be in charge of executing:

    commands[command].run(params);

The commands accepted by this terminal are: **pwd**, **ls**, **cd**, **mkdir**, **echo**, **cat**, **rm**, **mv**, **clear**, **help**, **man**, **urbandict**, **js**,

To work with paths, files and directories I implemented an object called filesTree which provides me with all the functionalities I need to work with a file hierarchy.

Files Tree

To develop a terminal that works with files and directories, first I proposed a tree type object that could perform operations such as adding nodes, removing nodes, moving nodes, searching nodes, etc.

This structure is based on a set of nodes, where each node contains a reference to the parent node and, in the case of a directory, references to the children.

Then I can implement in a very fast and simple way any command that is requested as well as ls (list child nodes), mkdir (create a new directory type node), mv (move a node) etc.

In addition, working with a tree structure allows me to navigate between the nodes using very simple recursive functions.

Local Storage

In the local storage both the file tree and the history of entered commands are stored. To be able to save a circular tree structure like the one we have created (Children nodes save references from the parents and vice versa), we cannot convert to string the object directly. To do that, I have implemented 2 intermediate steps, serialize and deserialize.

To serialize the tree, I go through it recursively exchanging all the references to an object for an id that represents that object, and I store this id-object pair in a new object. This way I can save this new object I create in the local storage.

To deserialize the tree we do the opposite process. We go through this new object and transform each id to the object it identifies, creating again a tree structure.

Keyboard shortcuts

• Up Arrow: See the previous command entered
• Down Arrow: See the following entered command
• Ctrl + L: Clear Terminal
• Tab: Autocomplete with the following available file/directory

History

To save each entered command we use an array which we save in the local storage every time we enter a new command.

Urban Dictionary API

To call this api from the terminal I have created a command called urbandict which receives a word as a parameter.

This API receives the word that the user has written and returns a list with all the existing definitions in the Urban Dictionary web of that word.

ENDPOINT: https://mashape-community-urban-dictionary.p.rapidapi.com/define

To ask for the definitions of a word we add that word in the term parameter:

https://mashape-community-urban-dictionary.p.rapidapi.com/define?term=hair

API Response

    {
    "list": [
        {
            "definition": "A separate creature that happens to live on your head, hard to [tame]. Ferociously attacking it with scissors, dye or hairproducts may [euthanize] said beast for a short while but beware of [angering] it.",
            "permalink": "http://hair.urbanup.com/4950762",
            "thumbs_up": 186,
            "sound_urls": [],
            "author": "nofu",
            "word": "hair",
            "defid": 4950762,
            "current_vote": "",
            "written_on": "2010-05-09T00:00:00.000Z",
            "example": "[Lizzie] tried hot-ironing her hair to [submission] but oh [woes], it was raining and the beast came out on top in the end anyway.",
            "thumbs_down": 52
        },
        {
            "definition": "A growing substance found mostly [on the head]. Hair is largely [amino] [acid] based and can come in a veriety of colours e.g. brown, ginger, black or blonde.",
            "permalink": "http://hair.urbanup.com/109686",
            "thumbs_up": 527,
            "sound_urls": [],
            "author": "Jim Hodgson",
            "word": "hair",
            "defid": 109686,
            "current_vote": "",
            "written_on": "2003-04-28T00:00:00.000Z",
            "example": "[Tomorrow] I will [comb] [my hair]",
            "thumbs_down": 236
        },
        ...
    },
}

Incidents Record

• Dividing a path into tail and name has given many problems as there are many corner cases that are hard to find
• Auto complete with tab has given some strange behavior but is not a problem for the execution
• Moving a directory gave problems if the current directory was underneath the moving node. This is now fixed
• Saving the tree in the local storage gave an error. I have solved it through a serialization process

Lessons Learnt Record

• Creation of regex for the split of a valid linux path
• Serializing and deserializing a tree in a recursive way
• I have been able to implement one of my favorite data structures since its operations are recursive by nature and I have had a great time :)