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Now, in the last lesson, we created what is the basic structure of a love calculator using randomisation
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and Javascript.
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Now, wouldn't it be nice if we could give the user a custom message based on what they got as their love
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score?
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Now in order to do this we need a way of checking what score they got and responding differently based
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on that score.
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And to do that we need to use conditionals. The way that conditional statements work is, you can use the
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keyword if to evaluate a statement.
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For example, in this case, if the track is clear. And, if that statement is true, then it will carry out
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a particular sequence of code.
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But if that statement is false,
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so the track is not clear,
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then you can have an ELSE keyword that tells the computer what it should do instead
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in that case. And this, in programming, is known as control flow. We're essentially controlling the flow
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of our code depending on the current conditions.
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By the way I had a lot of fun building that toy train set in Keynote. In case anybody else is living
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in a cramped London apartment and you don't have the space for a full toy set, and you're probably too
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old to play with them anyways,
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Keynote is your best bet. Now,
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this is how we might express our little track scenario in code.
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So we have the keyword if,
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and then we have some parentheses.
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And inside the parentheses are some conditions.
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So if the track is equal to clear then we take the flow of the code into the curly braces straight after
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and then we run the function goStraight. However, if that condition is not true, i.e. track does not
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equal clear, then the code flows to the else statement,
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and we run the function turnRight instead.
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While this is an easy way of seeing how our code works, it doesn't look very good when we have lots and
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lots of code inside the if and else statement,
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so more commonly you'll see this code structured like this by Javascript programmers.
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So we say if, we test the condition, and that's followed straightaway by the block of code that will
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get carried out if that condition is true, and then we open up the else statement to specify what should
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happen if that condition is not true. And essentially, through the testing of these conditions, we get
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to control the flow of code,
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and that's why they're called conditionals. So let's use what we learned to edit our code in the love calculator.
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So we have a love score here and we know that we get a number between 1 to 100.
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So that will be the condition that we will test.
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So we will say if, which is the keyword here, and then we'll open up some parentheses to add our testing
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condition.
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So let's say that our condition was that loveScore is equal to 100.
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And in order to test for equality we're using three equal signs.
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And if that is true then this block of code will be executed.
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But if it's not true, i.e. else, then this block of code will be executed instead.
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So let's say that, if loveScore was equal to 100.
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Well that's pretty crazy, right?
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Then we should say something like, alert "Your love score is " this amount.
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And then we should give them an interpretation.
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Like, for example, "You love each other like Kanye loves Kanye.".
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But otherwise we just give them the plain old normal message where we tell them their love score.
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Now some might have realized that I would have to go through this many many times until I happened to
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get a love score that is 100, which is quite unlikely.
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I mean it's 1 percent likely, right?
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So what if we simply wanted to test for a range, say for example if the love score was between 70 and
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100, or if the love score was between 0 and 30?
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Well, in order to do that, then we would have to use something like greater than.
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So if love score was greater than 70 then we should get this alert,
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otherwise we get this simple one instead.
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So let's try this out and we get 58 on the first go.
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There we go.
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So we finally got above 70.
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We've got 76 percent.
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And we get told that we love each other like Kanye loves Kanye.
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I used to love Kanye.
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I thought I was Kanye. What if Kanye made a song about Kanye?
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Man that would be so Kanye.