In the slides above, we learnt the arrays allow us to represent a collection of values as a single value:
var myList = [2,6,5,3,10,-2];
We can inspect the value at a particular position in an array, and overwrite them. Remember that arrays are zero-indexed, meaning we start counting from 0 (e.g. the 1st element of the array is position 0, the 2nd is position 1, and so on)
console.log(myList[2]); // outputs 5
myList[3] = "R";
console.log(myList); // outputs [2,6,5,"R",10,-2]
(This is referred to in the slides) Create an array with the items 1, 2 and 4 in it, assigning it to a variable myArray
, and print it out to the console.
(This is referred to in the slides) Starting with var nums = [5,6,7,8]
, use appropriate array-related code to do the following:
For the tasks below, there are a number of array functions which will help you. Suppose var x = ['a','b','c','d','e']
:
x.push('f')
: Adds an extra item to the end of your array.x.concat(['f','g'])
: Appends ('concatenates') two arrays together, producing a new array. The array x
will be unaffected.x.join(", ")
: Joins the elements of an array into one string, separated by the provided separator. Here we'd obtain "a, b, c, d, e"
"1, 2, 3".split(", ")
: The opposite - splitting an string using the provided separator, to produce an array. Here we'd obtain [1, 2, 3]
x.length
: This gives the number of elements in the array, here 5. Note that length
is a property of the array and not a function, so use .length
not .length()
.x.indexOf('c')
: Locates the position of an element in the array. This expressions will evaluate to 2 (i.e. the 3rd position).pop
and split
.Write code that does the following:
x
.for
loop for printingWrite code that goes through each thing in items
and prints out "I like ....".
for
loop for summationWrite a function sumArray
which inputs an array, and outputs the sum of the items in the array. The last line of your code within the function should be return total
, which will cause your function to output this value.
for
loopsWrite a function arrayEvenLengths
which inputs an array of strings, and outputs a new array which tells you whether each string has an even number of letters. For example arrayEvenLengths(["One", "Two, "Four"])
would output [false, false, true]
. The last line within your function should be return yourArray
.
You could always avoid use of a for
loop by using the map
function, as described in the slides.
The variable board
contains the current state of a noughts-and-crosses board. The aim of the game is to get a row of three 'X's or three 'O's, either vertically, horizontally or diagonally. Write some code that determines whether board
is a winning game position. For example [['O','O','O'],['X','-','X'],['X','O','X']]
would be a win for 'O'. Your code should return true
if someone has won, and false
otherwise.