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In this video we add code to manipulate the Geolocation information so we can test notes from multiple locations while staying in the same location.
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[Jim Hoskins] So now we've updated our code so the calculation of distances
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probably works; however, we don't know for sure
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because all of our Notes have the same latitude and longitude
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which is the same as our current location.
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All of our Notes showing here with 0 would appear to have 0 distance
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between them and the note, and this Note up here with -1
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would indicate that we don't actually have a distance on that Note
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and -1 is sort of our escape value.
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So let's write some code to change the latitude and longitude
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if we're in a debug mode.
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So what I'm going to do is I'm going to add some code at the top of our NotesApp here.
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Now, this is all contained in a self-executing function
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so we can easily create a function and a variable without clouding up
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the global scope of our browser.
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So one thing I'm going to do is I'm going to create a variable
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called debug, and we'll set it to false; at least for now.
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So now we need to actually create a function that will change our coordinates
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ever so slightly every time we call this function.
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So let's call this function fuzzCoords
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and we'll take a (coordinates){ object.
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All we need to do is call coords.latitude
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and we'll do += to add to it and we'll get a random value
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by doing (Math.random()
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and (Math.random) returns a value between 0 and 1.
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And I want them to be equally weighted between adding and subtracting,
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so I'll subtract 0.5
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and I want to scale that degree down by one-tenth so we don't move too far
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in latitude and longitude from our location, so I'll multiply that by 0.1.
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You can change this factor right here
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if you want to make your coordinates really, really spread out.
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The larger this number, the larger the actual spread can be
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and the smaller the number, the closer to the true distance
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it will be after your fuzz these coordinates.
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We'll do the same for longitude.
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coords.longitude += (Math.random() = 0.5) * 0.1;
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Cool. So whenever we call fuzzCoords and pass it an object,
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it's going to actively modify that object so that we don't have to worry about returning it,
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although we could.
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So there's a couple of places that we want to potentially
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fuzz the coordinates when we get them, and that's everywhere we do a query
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for Geolocation data.
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So now, let's add the fuzzCoords to the code where we assign the coordinates
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to each of our Notes,
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and that's done in the new form view here in our Geolocation call
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where we get our attributes, latitude, and longitude from the coordinates object here.
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So what I'll do is add if(debug)[
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we will fuzzCoords(attrs); so this will change the latitude and longitude value
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by a small, random value.
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So to actually get this to work, we need to actually turn on debug
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and change this to true,
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and let's try it out in the browser.
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Let's refresh, go create a New Note,
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create a Fuzzed Note with some text
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and we will tag it with our location and save.
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And if we go to Nearest Notes and look at our Fuzzed Notes here,
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I can assure you this is not our current location.
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It is in a suburb slightly outside of downtown Orlando,
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so it will work perfectly.
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And let's go back to our Nearest Notes here
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and see if we click Locate if that Fuzzed Note shows a different value.
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Cool. So it's showing about 4.8 kilometers outside of our current location.
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If we were to go back and change all of these Notes' values,
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we should get a slightly different value for each one
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and now it looks like our location will work, so it's going by distance.
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I can create another Note and we'll do our Next Fuzzed Note
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and we will give it some text.
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We'll make sure it's Yes, save it out.
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If we go to Nearest Notes again, Locate to update our position
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and our sort, this Note is a little bit further away.
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If we take a look at it, it is quite a bit south of Orlando--
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a little bit even further than the previous note,
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and I would venture to guess that that is probably roughly 6.2 kilometers
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outside of where our current location is, based on my knowledge of Orlando.
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So it looks like our Location works.
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If we were to take this out and test it around town,
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we'd obviously want to turn off the debug since we would actually be moving throughout space
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and we'd want our latitude and longitude to be accurate,
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but for testing, this debug system works pretty darn well.
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