Assignment #6: Orbit Report

Introduction and Background

There are thousands of satellites orbiting the earth. You are tasked with updating a searchable, sortable table of satellites. For the purposes of this assignment, a satellite will be defined as any object purposefully placed into orbit.

Your table will have the following features:

  1. Satellites: Each row in the table contains data on one satellite.

  2. Search form: Filters search results based on matches to the entered text. Pressing enter or clicking the button triggers the search.

  3. Sortable columns: Name and Type column headers can be clicked, which will sort the table using that property.

  4. Counts: Displays the total number of satellites in the table.

Your completed assignment should look something like this demo app.


Please do not attempt this assignment until after your first lesson on Angular. It can be tempting to dive right in, but Angular is a broad topic, and you want to wait to have a solid understanding of the framework before you get started.

Setup and Starter Code

In Canvas, Graded Assignment #6: Orbit Report contains a GitHub Classroom assignment invitation link. Refer back to the GitHub Classroom instructions from Graded Assignment #0: Hello World for submission instructions.


Don't forget to run npm install before trying to run the starter code.

When you first pull down the starter code, your running application will look something like this:

Screen shot of browser showing http://localhost:4200 with a title, search box, and broken count box.

Example of running the starter code.


As you accomplish each task, commit and push your changes before moving on to the next item.

1) Display Orbit List Component

The main portion of the orbit report is a table of satellite data. When you first pull down and serve this angular project, you'll notice there is no such table on the page. That's because the angular component responsible for this table hasn't been added to the app's HTML.

To have the satellite table displayed, add the orbit-list component tag to the app HTML.

Screen shot of browser showing http://localhost:4200 with a table of 1 satellite.

Example of running app with the orbit-list component displayed.

2) Display Live Satellite Data

Now that you have the orbit-list component being rendered on the page, you can have the table change the number of rows displayed depending on the fetched Satellite data. This is a flexible web app!

  1. There is an array of Satellite objects in app.component.ts named displayList. In order to pass that array into the orbit-list, you need to learn a new Angular feature named input properties. Here, the term "input" refers to data being sent into the component.


    Angular input properties are not related to HTML input elements.

    To pass the displayList array into the orbit-list component, you need to learn new syntax.

    Modify the tag you added in the step above as follows:

    <app-orbit-list [satellites]="displayList"></app-orbit-list>
    1. [satellites] declares a new satellites property on the orbit-list component.

    2. ="displayList" sets the value of the satellites property to be the displayList array.

  2. Now, the orbit-list component has access to the fetched satellite data. To confirm this, change the orbit-list component html to use it's satellites property.

    When you can confirm that orbit-list has access to the satellite data, remove the single hard-coded satellite table row and replace it with code using an *ngFor directive to loop over all of the fetched satellite objects and display their information. In the new report table, each row represents a different satellite.

    The HTML table you build should look like the following.

View the app in your browser. Your table should look something like:

Screen shot of browser showing http://localhost:4200 with a table of 5 satellites.

Example of satellite table.

3) Highlight Space Debris

You need to make it easier to spot dangerous space debris in the satellite data. Inside of the Satellite class, there is a broken method called isSpaceDebris. This is meant to return true only when a Satellite object has this type.

To highlight space debris, you first need to fix this method. Next, use the method to add a warning class onto the table cell. There's already a css style rule to make any element marked with the warning class appear red.

  1. Repair the isSpaceDebris method in the Satellite class. isSpaceDebris returns true if the satellite type is 'Space Debris', and it returns false otherwise.

  2. Use isSpaceDebris to add the warning CSS class to the <td> containing the satellite's type. Use an Angular attribute directive to accomplish this.


    Refer to the section on changing styles with attribute directives.

    Screen shot of browser showing http://localhost:4200 with a table of 9 satellites, with Space Debris cell having a red background.

    Example of warning style adding a red background to Space Debris type.

4) Counting Satellites

orbit-counts is a component that shows the total number of satellites currently displayed in the table. Or at least, that's what it should do. Right now, it's just displaying NaN.

To fix this, you'll need to replace the NaN string with a structural directive to indicate how many satellites are on display in the table. Like orbit-list, the orbit-counts component has access to the array of fetched satellites using an input property called satellites.

The desired functionality is that the number displayed with change with the number of satellites displayed. Checkout this gif for reference. Note, you do not need to display the counts for each satellite type to pass the autograder, just use the satellite property to show the total number of satellites displayed.

Bonus Missions

1) Zebra Stripes

Alternate the color for every other row in the table. Choose whichever pair of colors you prefer, but the highlighting for space debris should still be distinct.

Alternating row colors.

2) Update the Search Feature

Modify the search feature to find matches using the orbitType and type properties.

If you completed the counting satellites bonus, use an *ngFor to loop over an array of the different types, instead of explicitly writing a <tr> for each satellite type.


You may have already completed this mission, depending on how you accomplished counting the satellites.

Submitting Your Work

In Canvas, open the Orbit Report assignment and click the "Submit" button. An input box will appear.

Copy the URL for your Github repository and paste it into the box, then click "Submit" again.