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You have completed JavaScript Loops!
You have completed JavaScript Loops!
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In programming, a loop is a way to repeat the same set of actions a certain number of times or until a specific condition is true.
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[MUSIC]
0:00
Hi, everyone, I'm Guil, a developer and
instructor here at Treehouse.
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In this course,
I'll teach you another fundamental concept
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that you'll use just about every day
in JavaScript programming, loops.
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[MUSIC]
0:20
In programming, a loop is a way to repeat
the same set of actions a certain number
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of times or
until a specific condition is true.
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For example, let's say you wanted to
display ten random numbers on a web page.
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Well, you could write the code
to generate a random number,
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then display it on the page.
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Then write that exact code a second time,
a third time,
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a fourth time, until you've
duplicated that same code ten times.
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Well, typing the same code ten times seems
like a lot of work, not only for you, but
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also for other developers who
might work with your code.
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Now, imagine you wanted
100 random numbers or
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a 1,000,
that would be a lot of repetitive code.
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Here's a better way, automate it, write
that code once, then have your program
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repeat it 10 times, or a 100, or a 1,000
times, that's exactly what a loop does.
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Think of a loop as a running track
with entrance and exit areas.
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Imagine you're putting
together a 10,000 meter race,
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you could build one really long path for
the runners to run on.
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But that would take up a lot of space,
it would take a long time to build and
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would be very expensive.
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Or you could create a much shorter path
that racers can run around over and
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over again.
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The oval shape of the track is a loop and
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a race requires the runners to run around
that track a certain number of times.
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When a runner has gone around
the track ten times, for example,
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then that runner has completed the race.
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Programming loops also look like this,
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the code you want to run more
than once is inside the loop.
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When you enter the loop, the code inside
it runs once, then it runs again and
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again until a particular condition is met.
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For example, when the loop has
run ten times, the loop ends.
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Loops are really common in programming and
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there are different ways to
write loops in JavaScript.
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Some use different mechanisms and
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syntax making certain loops a better
choice over others in specific situations.
2:10
You'll learn three types of loops in this
course, the while, do-while, and for loop.
2:16
Before we keep going, you should know
that I'm going to assume that you
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already know the basics of
JavaScript variables, strings,
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numbers, conditionals, and functions.
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So to help you succeed, you should
have completed the prerequisites for
2:29
this course.
2:32
You can review them in
the teacher's notes with this video.
2:33
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