//pass an array of numbers into a function and log each number to the console
function yourFunctionsName(arrayToLoop){
//Initialize 'i' as your counter set to 0
//Keep looping while your counter 'i' is less than your arrays length
//After each loop the counter 'i' is to increased by 1
for(let i = 0; i <arrayToLoop.length; i++){
//during each loop we will console.log the current array's element
//we use 'i' to designate the current element's index in the array
console.log(arrayToLoop[i])
}
}
//Function call below to pass in example array of numbers
yourFunctionsName([1, 2, 3, 4, 5, 6])
//this varible as the name implies is the amount of wanted loops
var amountOfLoops = 3
for (let i=0; i<amountOfLoops; i++) {
//code to run each iteration
}
/*
for (statement1; statement2; statement3) {
INSERT CODE
statement1 is executed before for loop starts
statement2 is the condition
statement3 is executed after every loop
}
*/
for (i = 0; i < 5; i++) {
console.log(i);
}
// Sample Data:
const days = ["Monday","Tuesday","Wednesday","Thursday","Friday","Saturday","Sunday"]
// Samle Data which has undefined items:
const days = ["Monday","Tuesday",,"Thursday",,"Saturday","Sunday"]
// This Post might be a good read, to see a few caveats and advantages:
// https://stackoverflow.com/questions/500504/why-is-using-for-in-for-array-iteration-a-bad-idea
//Classic For Loop using 3 expressions iterates all array indexes:
for (let i=0; i<days.length; i++){
console.log("Day: "+days[i])
}
//for..in iterates defined array indexes:
for (let day in days){
console.log("Day: ", days[day]);
}
//for..of iterates all array items:
for (let day of days){
console.log("Day: ", day);
}
//using array methods might be more suitable depending on the scenario:
days.forEach(function(day){
console.log("Day: ", day);
});
//available methods:
days.forEach()
days.map()
days.filter()
days.reduce()
days.every()
days.some() //this one is neat imo
...
//multiplying a given number by eight if it is an even number and by nine otherwise.
function simpleMultiplication(number) {
if (number % 2 === 0) {
return number * 8;
} else {
return number * 9;
}
}
How for-loops work
A for loop has 3 parts
I will go the through the first section, than the third and than the second.
The first part is where we will start, in this case, I want to start at 0.
for(let index = 0;)
than we say every time the loop repeats how much does it add?
In this case Im using numbers and adding 1 each time. so I say:
for(let index = 0; index = index + 1)
And the final part when do we want the loop to stop?
in this case I want it to stop at 10 so I will make my for-loop like this:
for(let index = 0; index < 10; index = index + 1)
Now I add the body to my for-loop
for(let index = 0; index < 10; index = index + 1) {
}
And now inside the body I run the command: console.log(index);
this will run the for-loop
for(let index = 0; index < 10; index = index + 1) {
console.log(index); } //-> 0 1 2 3 4 5 6 7 8 9
It will run to 9 not 10 because it did run 10 times, but
the index started at 0 not 1