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Amsterdam CODE100 Quiz and Knowledge rounds

Audience Shout Out Rounds

Shoutout Block 1

How many arrays with how many elements does this console.log() return?

function A() { return [[1,2,3],[4,5,6],[7,8,9]] }
function B() { return [1,2,2,5] }
function C() { return [1,4,4,2,[1,1]] }
console.log( [...new Set( 
    [ B(), C(), A() ].map (
        e => e.flat() 
) ] )


Solution: One array with 9 elements. Each array gets flattened into a single one and the result is turned into a Set, returning only the unique elements. The last flat() turns it into one array. It is the classic question of “If you have 1 hay stack and you add two haystacks to it, how many do you get?”

Shoutout Block 2

What does the following CSS do?

  border: 2px solid firebrick;


Solution: the not() selector checks if an image has an alt attribute and if it does not it adds a border around it. You can still provide other ways to give an image alternative text than the alt attribute, hence it’s not the third option.

Shoutout Block 3

How many of the following are not valid named CSS colours:

Powderblue, Papayawhip, Honeydew, Peru, Greysmoke Blanchedalmond, Pistachio, Chocolate, Snow, Bisque Gainsboro, Milkshake, Lavender, Peachpuff, Ivory, Ebony


Solution: Greysmoke, Milkshake, Ebony and Pistachio are made up. Amazing if you think about Ivory being a valid one. If you feel like playing a game with named colours, I (made one some time ago](https://codepo8.github.io/css-colour-names/).

Shoutout Block 4

What does the following CSS do?

a[href^=http]::after {
  content: " ↗";


Solution: The selector matches links with an href attribute that starts with http and adds an arrow after them. Unless you have gopher or ftp links that should match them all.

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