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So far, you've learned useful array
methods like push, pop, shift, and

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unshift.

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These are just a few out of the dozens
of array methods available.

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As you gain more experience with arrays,
you'll want to start learning and

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experimenting with other
more advanced methods.

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So in these next couple of videos,
I'll teach you other common and

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useful array methods, join(),
includes(), and indexOf().

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You don't need to follow along just yet.

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You will get to do some programming
with these methods soon.

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You can also review the code examples
from this video in the teacher's notes.

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Let's first look at the join method.

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The join method takes an array and returns
a string holding all the elements in

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the array, separated by a supplied
character, like a comma or a colon.

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This is a great way to display all of
the items in an array on a single line.

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For example,
here I have an array named daysInWeek,

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holding all the days in the week.

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I can convert this array into
a single comma-separated

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string by calling the join
method on daysInWeek.

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In the JavaScript console,
I'll type daysInWeek.join().

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Notice how this returns one string
with all the daysInWeek array elements

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joined and separated by a comma,
by default.

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You'll usually pass
the join method a string,

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specifying the character you want to
separate the elements of the array.

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You can pass any character to
the join method, like a comma,

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colon, semicolon, even a letter.

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In fact,
you can pass more than one character.

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For example, you can pass a string
containing a comma and a space.

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The comma and space appear after each
element in the array, except the last one.

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To separate each with a space, you'd
pass join a string with a space in it.

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Another array method that's extremely
useful is the includes method.

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includes determines whether
an array includes a certain value

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among its entries, and
returns either true or false.

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If the value you passed to the includes
method is in the list of array elements,

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includes returns true.

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If the value is not in the array,
it returns false.

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For example, here I have a fruit array.

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I can search if apple is in
the array with the includes method,

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by typing fruit.includes the string apple.

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This returns true,

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because the string apple is indeed
a value in the fruit array.

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If I pass includes the string pear,
it returns false,

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because pear is not a value
in the fruit array.

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Keep in mind that includes is
case-sensitive, so it treats uppercase and

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lowercase characters differently.

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For example, if I pass includes Apple
with a capital A, it returns false.

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Finally, you can use the indexOf
method to return the index or

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position of an element inside an array.

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For example, apple is the first
element in the fruit array,

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so fruit.indexOf('apple')
returns its index value, 0.

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If I pass it grapefruit,
indexOf returns the value 2,

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since that's the index
position of grapefruit.

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Let's see what happens if the value
passed indexOf is not in the array,

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for instance fruit.indexOf('pear').

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Pear is not in the fruit array,

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so notice how the indexOf
method returns the value -1.

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And if I pass it kiwi, it also returns -1.

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indexOf returns -1 only when it
cannot find the index of an element.

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You can learn why it's -1 in
the teachers notes with this video.

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And while you're there, check out other
handy array methods you might come across.