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How do I solve the ReferenceError in my API calls from my UI?

I have done a microsoft tutorial called Web API with Javascript
I now have a UI made with Javascript and HTML which looks like this:
How do I use the UI? I keep getting a Reference Error. Is there a specific syntax I am supposed to follow when I add and edit something via APIs?

In the future, please copy and paste error messages into your question. I would normally copy and paste the error message in my answer, but I don't want to type it all out :)
The errors (red) mean that you're trying to use JavaScript that is not defined yet. The warnings (yellow) are the reason why.
The second warning says that it could not load the JavaScript. That explains the errors. The first warning might be the reason why. It's saying that the MIME type is empty, when it should be application/javascript.
But you said in the comments that the site.js file is empty when you try to access it directly. Did you save all the JavaScript in step 4 of that tutorial to site.js?
And what are you using as a web server? IIS Express?

Debugging Ember JS -- Identifying line in code that causes an error

So I'm getting the following error:
Uncaught Error: Assertion Failed: The key provided to get must be a string, you passed undefined
Should be easy enough to fix, if there was any indication of the line in my code that causes that error.
Using the chrome console, I click on ember.debug.js:6254 next to the error, which just shows me the ember code that throws the error. I can expand the error, but I just get a bunch of functions that can't be clicked on and no indication where they come from.
Can someone please help me figure out how to identify the line in my Ember code that is causing the error.

I've gotten this error before. It happens when you call get() in any of its forms (Ember.get() or this.get() or get(this)) without a string as the name of the property you want to retrieve.
You should be able to find the source of the error by auditing your application for wherever you call get() and making sure you pass the property name as a string. E.g., Ember.get('model.someProp') or this.get('someProp') or get(this, 'someProp').

This should be a comment but I can't, so here goes:
Iam new to Ember and have been spending quite a long time debugging. Remember that long stack of function calls that chrome's console shows.
Look for anything other than ember.debug.js...especially those marked (anonymous function) and files with names vendor.js or app-name.js

Usually in software development when debugging your best friends are going to be console.log() or alert() (in the case of JavaScript). Usually you have to figure out if your getting what ever is that you passing to your function by consolelog everything until you find your bug. Ember sometimes will not tell you what is exactly the error because does not know where exactly is coming from.
...computers are annoying but we love them....
here are some articles from Mozilla developer and Google on how to debug JavaScript.

I had a NULL value in my database which I wasn't accounting for in my app. In my case, it shouldn't have been NULL in the first place, so after giving the record a value in my database the problem disappeared.
I agree the error message is not very helpful.

Beginner programmer stuck on HW assignment - using Javascript to pull information from API

I am in a beginner programming class and am struggling with our latest assignment. We've been asked to pull data from the Forecast IO weather API and return it to a HTML static page. I've gone into the Developer Tools > Console Log to find the variables that (I think) I need to query, define, and display.
Based on the screenshot below, I think I need to write the following script, but its returning as an undefined variable. Can anyone help me and let me know where I'm going wrong?
The code I've tried so far:
var Latitude = document.getElementById("hourly.latitude")

You just need to use:
var Latitude = hourly.latitude
as hourly is a Javascript object and not an html element of the page.
See more information here Javascript object reference

Anchor element's pathname returns undefined in Rhino with env.js

I have run into an issue that I believe is rooted in the implementation of anchor tags in Rhino. Although I am utilizing env.js, I suspect perhaps I am not configuring something correctly.
In particular, my issue occurs while I am attempting to write unit tests against code written for an angularjs application. When I include angular.js (versions 1.2.1 to present), I get the following error:
TypeError: Cannot call method "charAt" of undefined
I am convinced the error is the result of this call to urlParsingNode.pathname since a console.log call reveals that the pathname object is undefined.
I traced the instantiation of the urlParsingNode to this line where we see that it is the result of a call to document.createElement("a"); Further down, we see that they set the href attribute in this line in hopes that the created anchor tag will utilize the browser to correctly parse the URL.
I have to believe I'm not the first to attempt JS unit testing for angular via Rhino, but thus far I've not successfully Googled myself to a solution. Any tips will be greatly appreciated.

Found it and fixed it. The pathname getter/setter simply was undefined for HTMLAnchorElement in env.js.
I submitted a pull request, but unfortunately the project looks all but abandoned. I also couldn't figure out how to build it out to a single file. It appears perhaps someone has taken it upon themselves to break it apart into require.js modules. Not a battle worth fighting for my use case.
So for anyone else who hits this issue, I have the code you need below. It belongs in the HTMLAnchorElement.prototype. In my copy of env.js 1.2, this prototype begins on line 8075. I added the following at line 8118.
get pathname() {
var uri = Envjs.urlsplit(this.href);
return uri.path;
},
set pathname(val) {
var uri = Envjs.urlsplit(this.href);
uri.path = val
this.href(uri.urlunsplit(uri));
},
FYI, my particular issue is resolved with this pull request.

Cannot read property 'variable' of undefined

I am navigating an object that contains an array of objects.
When I use chrome's js developer console I can grab the title property from the first item in the array i.e.
hello.example.array[0].title
this returns the title (only in the js developer console). However when I write a script to do this for me suddenly I receive this response:
Cannot read property 'array' of undefined
here is an example of my js
var theTitle = hello.example.array[0].title;
console.log(theTitle);
Why does the console find it correctly when my js does not?

Try selecting the expression in question in the script view and then use the Ctrl-Shift-E shortcut to evaluate in the console. Or, copy-and-paste from the script view into the console. Or, hover over the last component of the expression in the script view to see the value. In either case, you will most likely find that you've mistyped something, or are executing the script in a different context than that in which you are evaluating the expression in the console, etc.

Thanks to #Barmar, I realized I needed to view how I was going about grabbing the 'title' property.
My solution was in the context of other code and how the object was being created in the first place.
Thanks all for the help!
Edit 6 Years later:
This post has some popularity so I thought I would update it with a more valid answer...
Make sure your JavaScript actually has the scope/context of the object to begin with.
The JS Console is able to return it because it is being executed after the code has run.. whereas the JavaScript in question might be trying to access the variable before it is set.
So check if you have the right scope/context and that the code is not trying to access a variable before it has been set.