Objects

Functions

alert()

This function will display a given message to the user.

typeof()

This function returns the type of data produced.

For example, typeof(1) will output 'number'.

Questions

First the function alert() is called

Then the typeof() function is called

So in this problem we are trying to determine which type of data input the typeof() function is being fed

typeof('bird' != 'cat') will result in a boolean value, so our output is boolean, because that is the type of data that will be produced

Your suppose to get caught up in the fact that your dealing with a function passing the argument 'name'.

But pay no attention to this, just look at what the code is outputting.

The function is returning a variable called "say1," but say1 isn't given a value anywhere in our question.

Since we arnt given any information about this function's environment, its safe to say our output is going to be undefined.

This one is tricky, but in the case of alerting one string OR another, the first string will have the most precedence.

Because of this, our output is John, because John is the first string.

Nevermind the fact that John starts with a capital letter

If you were to alert(0 || "John") the output would be John, but if you were to alert(1 || "John") the output would be 1.

So you see how the rules can be weird.

This one is pretty straight-forward.

Note how we use console.log() to call function square(5), even though the function isnt established until later in the code.

This is okay and will still run.

So we pass 5 in place of n, so 5*5 = 25

This code first stores the string 'apple,' into the variable 'name'.

Next, a condition is set that says, "if true then name is equal to 'steve.'"

Now when name is alerted at the bottom, the output is apple.

This is because we never said what is true, all we said is if true, so the code disregards the conditional statement and outputs apple.

This code is all about type coersion

Javascript will convert the string '1,' into a number so it can be operated on.

So both of these values are equal to eachother after coersion.

1 is equal to 1, so the output is 0.

This one is about storing the contents of an array within one or more new variables.

An array is created holding the values 10, 20, 30, 40, 50.

Then the variables a, b, and c are established, but no value is given to them.

We then set a, b, and c into brackets. This is going to take '10' and assign its value to 'a'

If we were to console.log(a) the output would be 10.

So in the same way, '20' is assigned to 'b,' but now look at the '...' notation that comes before 'c'.

This notation will set the remainding values within the array (because 10 was given to a and 20 to b) and assign them to the value 'c.'

If we were to console.log(c) we would get an array containing 30, 40, and 50.

This is why c[1] is equal to 40, because 40 is the 2nd item of the array.

This code teaches us something important about transfering the contents of one array to a new variable.

First an array is assigned to the variable 'arr.'

Then the contents of that array is passed to the variable 'result.'

We then console.log the third item in the new array, which would expect to be apple, but it is pear instead. Why?

Well when we pass the contents of one array to another, any duplicate values are omitted.

So in this case, the array is passed from 'arr' to 'result.' During this process the second 'apple' is ommited from the array making pear the third item in the new array.

This code teaches us about concatination and the replace method.

First we say that a is equal to the string '2,' plus the string '8.'

This would normally result in 28, but look what happens next.

A new variable 'b' is established and is given the value "a.replace('2','3')"

This takes the string '2' in our original expression and changes it to a 3. So instead of 28, we get 38.

Javascript Challenge Study Guide