Arrays are variables that store lists of values:
var myArray = ["orange", "banana", "apple", "pear", "strawberry"];
// getting a value in your array:
// myArray[0] = "orange"
// myArray[1] = "banana"
You can retrieved a value from an array through specifying its index number. Arrays start with the index 0.
While loops allow you to repeat the same bit of code “while” a condition is true (!Careful, if your condition doesnt ever become false, you can crash your browser!):
var i = 0;
while (i < 10) {
console.log(i)
i = i + 1;
}
This can be adapted to cycle through a for loop:
var myArray = ["orange", "banana", "apple", "pear", "strawberry"];
var myArrayLength = myArray.length;
var i = 0;
while (i < myArrayLength){
console.log(myArray[i])
i = i + 1;
}
// or the other way around:
var z = myArray.length - 1;
while (z >= 0){
console.log(myArray[i])
z = z - 1;
}
to combine two arrays:
var myFirstArray = ["one", "two", "three", "four"];
var myOtherArray = ["potato", "oranges", "fish", "clementines", "eggs"];
var z = 0;
while( z < myFirstArray.length || z < myOtherArray.length){
var combinedString = myFirstArray[z] + " " + myOtherArray[z];
console.log(combinedString)
z = z + 1;
}
For loops are an alternate method of navigating incrementally through information. For loops have more security than while loops, and are more frequently used.
for (var i = 0; i < 10; i++) {
console.log(i)
}
To use with an array:
var myArray = ["orange", "banana", "apple", "pear", "strawberry"];
for (var i = 0; i < myArray.length; i++) {
console.log(myArray[i])
}
Javascript also has a Math object that allows you generate random numbers and manipulate values:
Math.random() // produces a random decimal number between 0 and 1
Math.random()*10 // a random decimal number between 0 and 10
Math.round(1.4) // rounds to the nearest integer
Math.floor(1.9) // rounds down
Math.ceil(1.2) // rounds up
Math.ceil(Math.random*10) // produces a random integer between 1 and 10
Math.abs(-10) // gives the absolute value of a number
Math.min(0, -100, 200, 2000) // returns the lowest value
Math.max(0, -100, 200, 2000) // returns the highest value