=## Overview

Learn to clean code with prettier and eslint and refactor React components.

Get Started

Let’s start from the beginning again.

  • Update JsObjects
    • slb
    • ./CreateSynbolicLinks (needed for semver-inc)
  • Navigate back to your repository
  • Branch: week07
  • Folder: week07-system-check-refactor
  • Navigate into folder
    • get-gist and choose Elven Create Concurrently
    • Run elf-concur, choose s for server

Eslint and Prettier

Install eslint and prettier

  • get-gist and choose Run ESLintRc and Prettier
  • echo ‘build’ > .prettierignore
  • Run prettier, and it should clean both client and server.

We set up .prettierignore because we need to avoid trying to run prettier on our client/build directory.


  • cd server
  • get-gist and run Elven Node systemd Tools
  • Open setup-environment-service in WebStorm.

Here are the settings:

export SYSTEMD_DESCRIPTION="SystemCheck Refactor Service"

Add ELF_SCREF_PORT to both .bashrc and /bin/www. You need to export it from .bashrc.

var port = normalizePort(process.env.ELF_SCREF_PORT || '30030');

NOTE: Ultimately, we may want to put these exports in .my_bash_aliases.

Execute run-setup-service and confirm that it works. Use the q key to exit.

We also need to support the SETUP_LINUXBOX environment variable. Append this to the appropriate place in your service file completing the steps above:


Of course, the user name (bcuser) might change depending on where you run it from. If you move from Pristine Lubuntu to EC2, for instance, just execute run_setup_service to automatically change bcuser to ubuntu on all lines in the service file that use it.

Push and Tag

At this point, you should check that you have completed the [Script Master Push and Tag] assignment.

Push and tag:

elf-tagger "Completed setup phase" "week07-system-check-refactor"


Use meld to copy the key files from SystemCheck into this project.

  • server/app.js
  • server/routes/script-pusher.js
  • client/src/App.js

Radio Buttons

Add radios to render put this before the return statement in render:

const radioLocal =  (
      <div className="container">
          <form onSubmit={this.handleSubmit} >

              <div className="elf-form-field" >
                  <input type="radio" name="app-choice" value="CpuInfo" id="elf-radio-cpu" onChange={this.handleChange}/>
                  <label htmlFor="elf-radio-cpu">CpuInfo</label>

                  <input type="radio" name="app-choice" value="VersionCheck" id="elf-radio-version" onChange={this.handleChange}/>
                  <label htmlFor="elf-radio-version">Version Info</label>

              <div className="form-group">
                  <button type="submit" className="btn btn-primary">Run System Script</button>

Modify render

Put this in the render method:

    <button onClick={this.runFoo}>Run Foo</button>

The key point is the JavaScript JSX expression {radioLocal}.

And we handle it like this:

handleChange = (event) => {
    const selectedValue = event.target.value;
    console.log('HANDLE CHANGE', selectedValue);
        selectedValue: selectedValue


handleSubmit= (event) => {
    this.setState({allData: ''});
    console.log('A name was submitted: ' , this.state);
    //if (this.state.selectedValue === 'cpu') {


I’ll talk you through the refactor.


Other than systemd reated issues, I think I see three issues that are central to deployment.

  1. Create a script to automate running the build step in the client.
  2. Create a .gitignore file for the server
  3. Handle the case where we change branches on a deployed app.

The Build Script

Create a bash script file called build-copy. This script is designed to be run from the client directory. It begins as usual with:

#! /usr/bin/env bash

Declare a variable called SERVER_DIR that points at the public directory in the server folder. This will be a relative link that starts one directory closer to the root than the client directory : **../**

Now run the build:

npm run build

The next three lines will all use the SERVER_DIR variable. They:

  • Delete the file called precache-manifest*.js from server/public
    • The part where I place the wildcard (*) will differ every time we build.
  • Delete the static directory from the server/public
  • Recursively copy the contents of the build directory into server/public

NOTE: Only write the words server/public once: in the declaration for SERVER_DIR. The rest of the time, when you need to refer to that directory, use $SERVER_DIR. And once again, you will probably want to use a relative path in the definition of SERVER_DIR.

When you are done, you should be able to run the script to perform a build, delete the old files from the SERVER_DIR, and copy in the new ones. It’s not that these steps are hard to do without the script, but that the script makes the task simpler, and saves us from making a type that might caues trouble when deleting or copying files.

I suggest storing the build-copy file in your scripts directory and creating a symbolic link to it from your client directory. (It makes sense to also create a link to it from your ~/bin directory, but I want you to also create one from your client directory so I can use it while grading.)

The .gitignore for the Server

A .gitignore file belongs in the server directory. I think this covers it:


Changing Branches

Once we start a systemd service running, problems can occur if we switch branches in our repository. For things to work smoothly, each branch would need to contain more less identical code for a the directory hosting the service. This is not likely to be the case.

I can think of two solutions:

  1. Copy the code for the program out of the repository and point symbolic link in the ~/bin directory to the copy.
  2. Have two copies of your repository on your hard drive: one in your ~/Git folder in which you do your work, and one in a ~/Deploy folder which contains the code for your services. Always having working code in the master branch and always have the code in ~/Deploy pointing at master.

Of these two solutions, the second seems less likely to cause problems and simplest to maintain. The only draw back is that it takes up more disk space.

Turn it in

Make sure prettier and eslint come back with no errors when run from project root, client, or server.

Set up systemd to run locally, but not on EC2.

Tag and push with script:

  • elf-tagger “Completed system check refactor” “week07-system-check-refactor”


Issues sometimes surface with the environment variable SETUP_LINUXBOX. On my system it looks like this:


In our JavaScript code we access that variable like this:


In systemd service files, we set it like this:


Though the username can differ. In ~/.bash_aliases it gets set on line 14


You will need to put the path in conn.exec when running a remote call to a file found in the SLB directory.