JavaScript JavaScript Loops, Arrays and Objects Tracking Multiple Items with Arrays Build a Quiz Challenge, Part 1 Solution

Michael Humenick
Michael Humenick
1,138 Points

I do not understand arrays at all

Hey guys, I have been understanding JavaScript just well until I reached this part. Could somebody please explain how arrays work?

Thanks in advance!

Steven Vallarsa
Steven Vallarsa
Full Stack JavaScript Techdegree Student 8,372 Points

Yeah, arrays can be mind-bending, especially when you're dealing with multi-dimensional ones like in this exercise. Arrays are basically a big chunk of memory devoted to a list of items under one variable name.

Think of a one-dimensional array like a train, each car being an index in the array. The engine is the array name and doesn't count in the number, and each train car after is indexed by a number starting at zero. You put things in each car and can access them with the square bracket notation. so instead of a accessing a variable with one variable name, you access it by array name and square brackets arr[0] With more dimensions you keep adding square brackets to access the elements within. arr[0][0], etc... Like accessing room [0] in train car [0] in train arr.

That's probably not helpful, but I'm sure you can find better descriptions online.

1 Answer

MFrank Johnson
MFrank Johnson
4,961 Points

Agreed. Arrays can be mind-bending [if you let them]. However, a strong understanding of array basics is important if you ever expect to evolve your Javascript code game beyond a hobby. Try these commands in the Chrome console for yourself. (Remember, '//' are comments ...) You'll want to type everything except the comments.

// START CONSOLE

//-

// Create an array named 'arrayColor' which contains colors!

let arrayColor = ['blue', 'green', 'yellow'];

//-

// Make the console show the array and its contents.

arrayColor

// The above command will show the following output indicating an array with 3 elements.

// > (3) ["blue", "green", "yellow"]

//-

// If you click on the little arrow in front of the #3, you should see something similar to the following.

// (3) ["blue", "green", "yellow"]

// 0: "blue"

// 1: "green"

// 2: "yellow"

// length: 3

// proto: Array(0)

//-

// Show the color of the sky in the console.

console.log('The sky is ' + arrayColor[0]);

// The above command prints 'The sky is blue' to the console.

//-

// Show the color of grass in the console.

console.log('Grass is ' + arrayColor[1]);

// The above command prints 'Grass is green' to the console.

//-

//Show the color of the sun in the console.

console.log('The sun is ' + arrayColor[2]);

// The above command prints 'The sun is yellow' to the console.

// END CONSOLE

Hope that helps.

Want to test your understanding? Write a command to the console using your new array that says 'blue and yellow make green'. Add your answer here and we'll see if you got it.

Good luck.

Best, Frank