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April 4, 2016

“Angular: Getting Started” Problem Solver

This blog post supports the sample code for the “Angular: Getting Started” course on Pluralsight, identifying common issues along with their solutions.

Revision History

November 8, 2018 – This course was updated for v7 as documented here.

July 11, 2018 – This course was updated for v6 as documented here.

August 10, 2017 – This course was updated to include the Angular CLI, the new HttpClient in v4.3, and more as documented here.

October 18, 2016 – This course was updated for the final release of Angular 2.

The content of this post is based on Angular version >= 2.x unless explicitly stated otherwise.

The sample code can be found here: https://github.com/DeborahK/Angular-GettingStarted. The folders in this repo include:

  • APM–Start: The starter files. Use this as a starting point to code along with the course.
  • APM–Final: The completed files.

Please post to the Discussion tab for the course if you experience an issue not found in this post. Thanks!

Data Typing Issues

Problem: Odd typing issues such as Type ‘EventEmitter’ is not generic, or similar.

VS Code has been a bit too “helpful” with adding import statements and sometimes adds an incorrect one. For example, it may add the node EventEmitter instead of the Angular EventEmitter.

Solution: If you see a data typing error, first check your import statements at the top of the file and ensure they are correct.

Images Don’t Appear

Problem: Clicking on “Show Image” does not show the image, only a box with the image name.

If you look in the browser developer tools and see an error with the images, the site providing the images (openclipart.org) may be down.

Solution: You have several options here:

  • Try again later when the open clip art site we use is back up.
  • In the products.json file, replace the URL’s for the images with URLs to other images as desired.
  • Continue on as is. You can confirm that the button works by seeing the product name appear in the image column. The image itself is not necessary for successful instruction.

No Generated Test for Module

Problem: The command:

ng g m products/product --flat -m app

Does not generate a test as shown in the course.

Solution: That is new correct behavior.

An Angular module has no code to test, so generating a test for a module did not make sense. The Angular CLI was recently changed so it does not generate a test for the module. This will be changed in the course the next time the course is updated.

npm Issues

Problem: Error when using `npm install`.

There are several possible solutions depending on the source of your problem.

Solution 1: Ensure you have a current version of npm installed. The course was tested with node v6.5.0 and npm 3.10.6. If your version is significantly older, it may not work. Use node –v and npm –v to check your versions. To install a newer version of both tools, use this link: https://nodejs.org/en/download/current/

Solution 2: It may be a permissions problem. Try the steps found here: https://docs.npmjs.com/getting-started/fixing-npm-permissions

Can’t See Stars

Problem: Can’t see any stars.

The stars are displayed using font-awesome, so if no stars appear, this often means that font-awesome was not installed or imported correctly.

Solution: Re-watch the portion of the video detailing how to set up and import font-awesome: https://app.pluralsight.com/player?course=angular-2-getting-started-update&author=deborah-kurata&name=angular-2-getting-started-update-m4&clip=1&mode=live

At time code: 2:18. As per the video …

To install font-awesome use:

`npm install font-awesome`

Be sure you specify font-awesome (with a dash) and not fontawesome as the later is something else and won’t work.

To import font-awesome, in the style.css file:

`@import “~font-awesome/css/font-awesome.min.css”;`

 ‘Cannot read property ‘config’ of null’ on ‘npm start’

Problem: When typing ‘npm start’, receive the error: ‘Cannot read property ‘config’ of null’.

This almost always means that you are missing the .angular-cli.json file. If you are using a Mac, this is often because the Mac sees files that begin with “.” (dot) as system files and hides them or won’t copy them if copying a folder.

Solution: Go back to the original repository and manually copy the .angular-cli.json file into your root (APM) folder. You may need to perform a Command Shift . to show the hidden files.

Setting Up Behind a Corporate Web Proxy

Problem: Error in installing typings when performing `npm install`. Error may be something like “Failed at the product-management@1.0.0 postinstall: ‘typings install’

Solution 1: npm may not be using your globally defined proxy setting. Try adding a .typingsrc file with the value: “proxy=http://myproxy.com:myport”

Solution 2: Try manually installing the typings by running the following command at the command prompt: `npm run typings install`

Solution 3: Try the updated version of the starter files: APM-Start-Updated. Later versions of Angular 2 changed how the types are accessed and using these newer versions often prevent some of the typings issues.

See these posts for more information:

NOTE: If the proxy requires authentication (which is usually true), please use this format

$ npm config set proxy http://login:pass@host:port
$ npm config set https-proxy http://login:pass@host:port

NOTE: If you do not have access to the proxy URL and port, you can install the missing typing manually following the steps posted by Joe Ballard in the comments for this post below. Note however that with Angular 2 final you need core-js and node NOT es6-shim. See the typings.json file for details.

I Don’t Want to use the Starter Files!

Problem: Some viewers prefer to build the code using the Angular CLI instead of using the starter files.

The instructions in the course were set up for viewers to use the Starter files. That way we could get going coding quickly, without having to set everything up first. I cover how to build an app from scratch using the Angular CLI in the “Building, Testing, and Deploying with the CLI” module later in the course.

Solution: If you want to build the code using the Angular CLI instead of using the starter files, you need to do the following:

1) Use the command: `ng new APM –prefix pm`

This sets the appropriate prefix for the child component we build later in the course.

2) Set up bootstrap:

1. Run npm install bootstrap –save
2. In the .angular-cli.config file, add the Bootstrap CSS to the styles array:

"styles": [ 
    "styles.css", 
    "../node_modules/bootstrap/dist/css/bootstrap.css"
],

3) Set up the folder for the data file used in the course:

In the .angular-cli.config file, add the api folder to the assets array:

"assets": [ 
    "assets", 
    "api", 
    "favicon.ico"
],

Can I Follow the Course Without Installing Node?

Problem: Some viewers can’t install node due to limitations on installation of external apps or proxy issues. In this case, it still possible to code along with the course.

Solution: Use Plunker! Plunker is a playground that allows you to work with JavaScript, TypeScript, and Angular without downloading or installing anything.

To use Plunker:

1) Access the Web site: https://plnkr.co/

2) Select “Launch the Editor” (big blue button in the upper left).

3) Drop down the list from the New button (big green button in the toolbar) and select Angular. (A box appears telling you that you have unsaved changes. Just click Yes to proceed)

This sets up everything you need to run Angular here instead of downloading node/npm and running it on your system.

Just use the New File link in the Files list on the left to add new files. To specify a subdirectory, just add the path to the file name when creating a new file. For example: “src/app/products/product-list.component.ts”

You should then be able to follow the this course using Plunker instead.

Port 4200 is Already in Use

Problem: When using npm start or ng serve you see the error: “Port 4200 is already in use”.

Solution: The Angular CLI serves the application on Port 4200. If you closed the editor without stopping the service, it may still be holding on to port. So when you try to run again, it sees that port as already in use.

There are several ways to solve this problem.

  • You can serve to a different port: ng serve -–port 4201 or similar. Or to serve and automatically open the browser: ng serve –o –-port 4201
  • You can kill the task holding on to the port:
    • On a Mac: sudo kill $(sudo lsof -t -i:4200) or sudo kill `sudo lsof -t -i:4200`
    • On a PC:
      • Open a command prompt as administrator
      • run netstat –ano | findstr :4200
      • kill the appropriate PID: taskkill /PID 10764 /F
  • You can reboot your system. This will release all of the ports.

image

Error Code 404 Resource Not Found

Problem: When attempting to load the products from the products.json file, a 404 error code is generated and the products.json file cannot be found.

Solution: You need to modify your .angular-cli.json file

In the course, I make the assumption that viewers will download the starter files for the code and “code along” from there following the same example. So I don’t mention any of the *other* steps that are required to code along “from scratch” or using other folders/files/names. (I instead cover how to build an Angular application “from scratch” and how to set up these files later in the course.)

If you are attempting to code along “from scratch”, you need to modify your .angular-cli.json file to look like this:

  "apps": [ 
    { 
      "root": "src", 
      "outDir": "dist", 
      "assets": [ 
        "assets", 
        "api", 
        "favicon.ico" 
  ],

This ensures that the Angular CLI finds the .json file in the api folder.

The Code Does Not Work in Internet Explorer (IE)

Problem: The sample application does not run, or it runs but nothing appears in the browser AND you are using Internet Explorer (IE).

Solution: You need to set up polyfills as part of your Angular application for the application to run correctly in IE.

As stated in Wikipedia: “a polyfill is code that implements a feature on web browsers that do not support the feature”

To set up polyfills, see the module entitled: “Building, Testing, and Deploying with the CLI” in the clip called: “ng new” at time code 2:51. Here is the link to that clip.

The AppRoutingModule Does Not Work

Problem: If you created an AppRoutingModule as defined in the “Revisiting AppModule” clip in the “Angular Modules” course module, the routes may stop working.

Solution: Order matters when defining routes. The AppRoutingModule must be *last* in the list of imports, after any feature modules. The details as to why are provided here: http://blogs.msmvps.com/deborahk/angular-route-ordering/

Something is Wrong and the Code Doesn’t Work

Problem: JavaScript development in general can be difficult, so often something can go wrong.

Solution: Here are some tips for when your code doesn’t work:

  • JavaScript/Angular are CASE SENSITIVE. For example: “*ngIF” and “ngif” won’t work, must be “*ngIf”. This includes names. For example “@Angular/core” won’t work, must be “@angular/core”. If you name a route “products” it must be called “products” everywhere, and not “Products”. If you name your interface “IProduct” it must be called “IProduct” and not “Iproduct”. And so on.
  • Check the developer tools and view the console. Angular errors are shown there. Sometimes a little error causes a large message in the console. Start with the first or second line of the message. That often tells you exactly what is wrong.
  • Watch for typographical errors and syntax errors in the HTML. Unlike most Web apps, Angular is *not* forgiving when it comes to errors in the HTML. A missing or incorrect closing tag could prevent the application from working.
  • Try stopping and restarting the local server with ‘npm start’ again. Sometimes, especially when working with pipes and guards, the local server needs to be restarted for the changes to be fully recognized.
  • Try using a file compare utility and checking your code against the code for the course. You can find the starter files and final files in the github repo for this course. AND you can find the code as it should be at the end of each module using the “Exercise Files” tab on the Pluralsight page for the course.
  • Take care when finding solutions on the internet. Be sure the solution is appropriate for your version of Angular. Angular changed significantly from the Angular 2 RC versions to the final Angular 2 release. So any information posted prior to Angular 2’s release in September of 2016 can lead you down the wrong path.

“Can’t bind to ‘ngModel’ since it isn’t a known property of ‘input’.”

Problem: You will see the above message in the console.

Solution: This normally means that you are missing importing the FormsModule in your AppModule (or feature module).

How Do I Debug Angular?

Problem: Here was the question from a viewer: “Since the ts is compiled to js, there is a disconnect there for tracing code back to the source files…what tools do you recommend?”

Solution: TypeScript creates a map file that maps the js to your ts files. The best way to debug is to use the Chrome browser developer tools. With them you can set break points in your ts code.

See this link for more information: https://developers.google.com/web/tools/chrome-devtools/

Can We Use SCSS Instead of CSS?

Problem: If you are using another style sheet tools, you may be wondering how to use them with Angular.

Solution: Here are some suggestions:

– If you use @angular/cli (like is used in this course) then you can use the info here: https://github.com/angular/angular-cli#css-preprocessor-integration

– If you use WebPack (but not the CLI), there is info here: https://github.com/AngularClass/angular2-webpack-starter/wiki/How-to-include-SCSS-in-components and here: http://stackoverflow.com/questions/38313971/how-to-use-sass-for-components-style-in-angular-2

– If you want to use systemjs as is, then you can add a build step to your process that builds the css from the scss and then use the css in the component.

– If you want to use a loader with systemjs and then reference the scss instead of the css in the component, check out this: https://github.com/mobilexag/plugin-sass PLEASE NOTE: See the warning it provides on using this with TypeScript.

Where Do I Go Next?

Problem: If you’ve finished the course, you may wonder where you should next on your Angular journey.

Solution: Here are some suggestions:

117 Comments

  1.   Jeffrey — February 27, 2017 @ 11:43 am    Reply

    Downloaded all course stuff from machine A(has internet access) and
    tried to running the tutorial in Machine B(No internet access).

    Installed VS Code successfully.
    Installed Node.exe successfully.
    Installed NPM by >npm install failed due to trying to download bootstrap and zone.js etc.

    Any workaround or solution? Thanks

    Error message is as following.

    ——————————
    C:\Jeff_Space\Angular\APM>npm install
    npm ERR! Windows_NT 6.1.7601
    npm ERR! argv “C:\\Program Files\\nodejs\\node.exe” “C:\\Program Files\\nodejs\\node_modules\\npm\\bin\\npm-cli.js” “install”
    npm ERR! node v7.6.0
    npm ERR! npm v4.1.2
    npm ERR! code ENOTFOUND
    npm ERR! errno ENOTFOUND
    npm ERR! syscall getaddrinfo

    npm ERR! network getaddrinfo ENOTFOUND registry.npmjs.org registry.npmjs.org:443
    npm ERR! network This is most likely not a problem with npm itself
    npm ERR! network and is related to network connectivity.
    npm ERR! network In most cases you are behind a proxy or have bad network settings.
    npm ERR! network
    npm ERR! network If you are behind a proxy, please make sure that the
    npm ERR! network ‘proxy’ config is set properly. See: ‘npm help config’

    npm ERR! Please include the following file with any support request:
    npm ERR! C:\Jeff_Space\Angular\APM\npm-debug.log

    C:\Jeff_Space\Angular\APM>

    •   deborahk — March 27, 2017 @ 1:07 pm    Reply

      Sorry for the delay in my reply. I don’t receive notifications when people leave comments.

      I assume by now you have resolved this issue?

      The way npm works is that it uses the internet to collect and install all of the packages required for your application. So you would need to run “npm install” on the machine *with* internet access *before* copying it all to the machine without internet access.

  2.   Prakalathan — March 6, 2017 @ 4:03 am    Reply

    I am following your Angular 2 from pluralsight.com . Can you please suggest some video or page tutorial to connect Angular 2 with Mongodb..

  3.   Pranal — March 8, 2017 @ 5:43 am    Reply

    Hello

    Thank you for the ready made setup and give a quickstart with such ease for angular2 and typescript.
    I was able to install and post npm start it opened the browser like said in the instructions.
    Problem is as i modify the app folder where i change the pagetitle from “welcome” to “welcome ABC” (only text change) it does not reflect in the browser. if i make any modifications in the html tags (say from oyur name Deborah Kurata to test) in welcome.component.html page, it renders the html in browser.
    Final it works for html contents/tags but if any change done to bindings it doesnt work and it remains the default title.
    note: did all resets and cache clearing.

    Please suggest/help.
    Main idea is to use your code and build my requirements after installation and setup. which i cannot do any changes.

  4.   Talha — March 19, 2017 @ 2:00 pm    Reply

    Hey Deborah,

    Thanks for a great Angular2 course for beginners.

    The discussion on your plural sight course is not available for comments anymore that’s why I’m posting here.

    I was doing “Retrieving Data using Http” module and got stuck while working with Observables.

    For some reason it’s giving me error when I add “do” and “catch” methods however I’ve added all imports including ‘rxjs/add/operator/catch’,’rxjs/add/operator/do’and’rxjs/add/operator/map’. If I remove do and catch then it works.

    The error says “Cannot convert type Observable to type Observable”

    I’ve found a resolution to that problem on Stackoverflow but couldn’t understand the difference. Below is the code which solved that issue.

    public getProducts = (): Observable => {
    return this._http.get(this.productApi)
    .map((response: Response) => response.json())
    .do((data) => console.log(data))
    .catch(this.handleError);

    I’m using @angular/http version 2.4.0 and rxjs version 5.0.1

    Can you help me out here and explain what is the problem and the difference between this and yours syntax?

    Thanks,
    Talha

  5.   naxas — March 21, 2017 @ 5:22 pm    Reply

    hi Deborah, on (Angular2 -Getting started ) building Nested Components: using Nested component, I am not able to display stars on under the 5 stars rating.

  6.   G. Dharmar — March 29, 2017 @ 8:46 am    Reply

    In the section “Retrieving Data with Http”,
    you have given _productUrl = ‘api/products/products.json’.

    What is the full Url. The above Url is not complete. But how it worked?

    •   deborahk — March 30, 2017 @ 9:02 am    Reply

      I wanted to ensure that everyone could execute the application without having to build a back-end service. So this url is pointing to the *local* api folder in the project. It is simply reading the local json file.

      In a “real” application, you’d add a full URL path (www.mysite.com/apm/api/products) and pull down data from some type of back-end web service.

      Hope this helps.

  7.   Tom — March 30, 2017 @ 1:58 pm    Reply

    I see in the downloaded course files there are two starter folders “APM – Start” and “APM-Start-Updated” the latter being for Angular 4. I chose to use the Angular 4. But after running npm-start I notice the files I have in my code directories appear quite different than the ones shown in the presentation. In order to follow closely with the presentation as I code along, please tell me which starter folder follows the presentation more closely, I want to avoid getting lost and starting over.

    •   deborahk — March 31, 2017 @ 8:45 am    Reply

      The original APM – Start files are the ones that match the course. Later versions of Angular 2 (and Angular 4) use a different file structure and some different boilerplate files. If you want to follow along exactly with the course, use the APM – Start (not APM – Start Updated) folder.
      Hope this helps.

  8.   Abdollah — April 2, 2017 @ 10:50 am    Reply

    Hi Deborahk,

    I tried the following and can’t understand how this works:-

    1- opened the URL of the Acme project in chrome.
    2- opened the same URL in another incognito window.
    3- opened the page (Product list) in both windows.

    I noticed that when typing something or changing the value of the filter text box, it is automatically typed in the other window !!! How could that happen. Isn’t there a session management for angular? These should be two separate users. How changing some text field affects the other user’s same text field?

    Thanks in advance.

    Abdollah

    •   deborahk — April 3, 2017 @ 1:44 pm    Reply

      I assume you are seeing this behavior with localhost? That’s because of the lite-server used when running in development. You won’t see the same thing when doing to production and using a “real” back-end server.

  9.   Sachin Dave — April 2, 2017 @ 9:09 pm    Reply

    Hi, this is very good blog. It has helped me trouble shoot major issues we faced with initial Angularjs2.0 code setup.
    Thanks, Sachin Dave

    •   deborahk — April 3, 2017 @ 1:35 pm    Reply

      Glad it helped!

  10.   Swamy — April 13, 2017 @ 1:49 am    Reply

    Hello Debora,

    Could you put me on the right direction on how to deploy Angular 2 application on the shared web hosting server please?

    Do I need a Windows Server or Linux? would be nice to have it on the Windows if its possible please as i can also have Web API service as well.

    Many Thanks

    Regards
    Swamy

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