http://www.codequizzes.com/topics/26/quizzes/84

js-codequiz

Perform these exercises in the JavaScript console of your favorite web browser.

What does the following expression return?
> 3 + 2;

5
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What does the following expression return?
> typeof(3);

number
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What does the following expression return?
> typeof(3) === typeof(4.32);

true
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What does the following expression return?
> 5 / 0;

Infinity
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What does the following expression return?
> 3 / "bob";

NaN
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What does the following expression return?
> NaN === NaN;

false;
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What does the following expression return?
> typeof(NaN);

number
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What does the following expression return?
> isNaN(NaN);

true
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What does the following expression return?
> Math.pow(2, 3);

8
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Describe how the following expression assigns a variable to a value.
> var first_name = "cindy";

first_name is instantiated as a var when "var first_name" is typed; it is initialized when it is set equal to "cindy"
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What is the value of the hello variable in the following expression?
> var hello;

undefined
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What does the following expression return?
> var y;
> y === "cool";

false (because y was declared but not assigned to anything, so it is undefined, therefore not eq to anything)
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What does the following expression return?
> "some" + " person";

some person
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What does the following expression return?
> var first = "Bart";
> var last = "Simpson";
> first + " " + last

Bart Simpson
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What does the following expression return?
> "cool".length;

4
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What does the following expression return?  Explain the answer.
> "phat" === "phat";

true--they are the same in both value and type
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What does the following expression return?
> typeof("cats");

string
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What does the following expression return?
> 3 + "bob"

3bob
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Round the number 4.87 to the nearest integer.

Math.round(4.87);
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Divide the number 6 by the string "2" and explain the result.

3--because js can't divide a number by a string, it converts the string to a num and performs the result
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What does the following expression return?  Explain the result.
> 3 * "bob";

NaN--because js can't multiple a number by a string, it tries to convert the string into a number and learns that "bob" is not a number.
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Declare the variables x and y.

var x, y;
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Set the variable hobby to the string "programming".

var hobby = "programming";
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What does the following expression return?
> var sport; 
> sport === undefined

true
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Demonstrate that "brogrammer" has the type "string".

typeof("brogrammer");
string