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OK so it's time to learn about another type of loop in javascript called the for loop.

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So the for loop is similar to the while loop and that they both let us repeat code.

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They're a little bit different in their syntax.

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So our objective is here.

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You want to understand the purpose of for loops why you use one versus a while loop.

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You want to write valid for loops and then compare and contrast while loops and for loops.

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So to start here's a recipe for a for loop.

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We write the word for a keyword and then in parentheses there are three parts.

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And so I've some them up as the initialize the condition and the step.

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So this will take a little bit to sink in and we'll clarify this over the next few slides.

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But the key takeaway here is that we write the word for we have parentheses three different things go

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in the parentheses and then we have curly braces.

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So here's an example.

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This is how you print the numbers from 1 to 5 with a for loop.

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So we start with four.

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Then we create a variable.

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I'm calling it count and set it equal to zero.

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In this first chunk then we have our condition while count is less than 6.

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And then we have our increment which is going to add one to count.

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So this is conceptually very similar to the wildlife's who've been writing.

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So you can see the equivalent while loop down here.

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The big difference is that this is just shorter and the other difference is that this variable count

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only exists inside the loop.

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So this variable for a while loop must be initialized outside so that we can use it here in a for loop

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.

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We can make a variable that exists only for a moment inside of this loop.

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So to go over this one more time we're making a variable called count and it starts at zero every time

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through the loop.

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We add 1 to count and we keep going while count.

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It's less than six.

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So the first time we run this count is zero.

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We printed out the next time we've added 1.

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It's still less less than 6 so then we printed out and we keep going until count is six.

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It's no longer less than six and the code stops running.

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So I'm going to copy this to my counsel and just demonstrate that I paste that in and we get 0 1 2 3

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4 5.

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So here's another example taking what we did of the while loop where we printed every character in a

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string but doing it with a for loop.

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So once again you can see we don't have to create this count variable outside of a loop like we do for

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the while loop.

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We can create a temporary variable and I use one called I.

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The reason I did that is that it's pretty conventional to see for loop variables be very short single

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letter variable names like i or j or K and that's because they don't exist for any other purpose but

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to live inside the loop.

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So some people would argue it's better to keep them short.

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So over here I used to count.

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You can name these whatever you want but you'll see a lot more often in the real world.

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So we make a variable equal to zero every time through the loop.

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We're going to add one and we're going to keep going.

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While it's less than the length of the string.

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So the logic is the same as what we're doing here.

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Make a variable called Count set it to zero.

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Add one every time through and keep going while count is less than the length.

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So when I run this I'll copy it.

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Open up the console.

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Paste that in and we get H E L L O.

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And it prints one L with a 2 next to it.

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That's just how Chrome does repeated confidant logs.

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So to sum this up one more time instead of a for loop there are three parts.

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There's the Initialize where we declare a variable and set it to some initial value does not have to

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be zero.

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Then the next part we have a condition which is when this loop should keep running.

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And then the last part is our step.

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So what do we do at the end of every iteration.

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Do we add 1 to count or to subtract 1 Do we multiply it.

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There's all sorts of different things.

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Most often though you'll see it with a plus plus just like we did with while loops