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Test Multiple Conditions With the || Operator
4:04There are times you'll want to perform an action if either of the two possible conditions is true. In this video, you'll use the logical OR (|| ) operator to test multiple conditions.
You learned to use the and
operator to perform an action if two or
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more conditions evaluate to true.
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There are times you'll want to perform
an action if either of two possible
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conditions are true.
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For example, if it's hot or the indoor
pool is open, then I'll go swimming.
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In this case,
either condition can be true.
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It might be really cold outside, but
the indoor pool is heated and warm, so
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I'll go swimming.
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On the other hand, the indoor pool
may be closed but it's hot so
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I'll go swimming in the ocean.
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To run this type of test,
you use the or operator.
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It's called or because the entire
condition returns true if either
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condition one or
condition two evaluates the true.
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The logical or operator is
represented by two pipe characters.
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On most keyboard, the pipe characters
is on the same key as the backslash.
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Hold down the shift key to type it.
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All right, let's see how the or
operator works.
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Say you let someone agree to the terms and
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service of your website by typing
either yes or just the letter Y.
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They can type either one or other.
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Back in the console, I'll store
the response in a variable named agree and
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assign it the string yes.
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I can then use the logical or
operator like this.
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Agree strictly equals yes or
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agree strictly equals y.
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Just like with the logical and operator,
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there's really two
separate conditions here.
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Each condition gets tested separately and
produces its own true or false values.
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The value in the agree variable is yes.
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So the first test asks if yes
is strictly equal to yes, it is.
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So this first condition is true.
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The second test asks if yes is
strictly equal to y, this is not true.
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The role of the or operator here is
to ask if condition one is true or
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condition two true.
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In this case, one is true and
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that's enough this entire
condition evaluate to true.
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Let's continue with two more examples.
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I'll change the value and agree to just y.
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Now the first condition is false,
y is not equal to yes,
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but the second condition
y is equal to y is true.
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So the entire condition is also true.
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Remember, just the one test needs to pass.
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What if I set the value of agree to n?
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The first condition is false, and
the second condition is also false.
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In this case,
because neither condition is true,
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the whole condition evaluates the false.
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Keep in mind that you need to create
complete conditions on either side of
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the or operator.
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For example,
you can't do something like this.
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Even though it feels like
this should be correct,
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it really reads like,
if agree is equal to yes or y.
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Whatever appears on either side of the or
operator has to be a complete condition.
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'y' by itself isn't really a condition.
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So remember, you need to have
full conditions on either side.
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In the logical and
or operator examples,
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I've used just two conditions and
a single logical operator.
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You can actually have more
than one of each operator.
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For example, you can test if condition
one is true, and condition two,
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and condition three, and so on.
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There's no limit to the number of logical
and operators you string together.
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Just remember that with the and operator,
every single condition must be true for
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the entire condition to evaluate to true.
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If just one of the conditions is false,
then the entire condition is false.
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You can also string together
multiple logical or operators.
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In this case, only one of
the conditions needs to be true for
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the entire larger condition
to evaluate to true.
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And this example, if any of these three
variables contains an empty string,
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then the entire condition is true.
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