Loops & Arrays Review


Loops
- For
- While
- Do While


For loop

for( initial value;   condition;  iterative step)

for( var count = 2; count < 8; count = count + 3){
	alert(count + " aha hahaha");
}

output:
2
5


for(var i=0; i < 4; i= i +1){
	alert(i);

}

output
0
1
2
3

for(var i = 3; i >= 0; i= i - 1){
	alert(i);

}

output
3
2
1
0


while(condition){

	doThings();

}

example

while(score < 5){

	score = score + 1;
}
==================================================

do{

	score = score + 1;
} while( score < 5);

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===================================================

Arrays
- Index
- length
- push
- splice



var myMarks = [];

if(myMarks[3] == 80) goUni();

Makes no sense.


myMarks[0] = 90

myMarks = 90 is crazy


example

myMarks[0] = 90
myMarks[1] = 80
myMarks[2] = 9000
myMarks[3] = 10
myMarks[4] = 50


how compute average?

(90 + 80 + 9000 + 10 + 50) / 5
myMarks[0] + myMarks[1] + //is crazy, have btter idea

var total = 0;
for(var i=0; i < myMarks.length; i++){
	total = total + myMarks[i]	
}

var average = total / myMarks.length;


splice command

myMarks[0] = 90
myMarks[1] = 80
myMarks[2] = 9000
myMarks[3] = 10
myMarks[4] = 50


myMarks.splice(2,1)


2 - index to start splicing
1 - how many to splice



Push


myMarks[0] = 90
myMarks[1] = 80
myMarks[2] = 9000
...
myMarks[3] = 10
myMarks[4] = 50

myMarks.push(75);

now looks like

myMarks[0] = 90
myMarks[1] = 80
myMarks[2] = 9000
...
myMarks[3] = 10
myMarks[4] = 50
myMarks[5] = 75





var tester = []

tester[0] = 50
tester.push(40);
tester.push(70);

tester[1] = 38

50, 38, 70



for(var i = 0; i < 8; i++) names[i] = prompt("gime nameZZ!!");

for(var i = 0; i < 8; i++) names.push(prompt("gime nameZZ!!"));