While loop in CodeCraft

Function addTo(n)

Build n columns with heights from 1 to n, then build a tall column that has height the sum of all the numbers, (1 + 2 + ... + n).

function addTo(n) {
    let sum = 0;
    let i = 1;
    while (i <= n) {
        column(i, -20, i, 'box_light_blue');
        sum += i;
        i++;
    }
    column(-2, -20, sum,'box_red');
}

// call the function with input    
addTo(5)

See in the picture, the numbers (1,2,3,4,5) are indicated by blue columns, and the red tall column is the sum of all numbers (1+2+...+5 = 15).

Question: can you rewrite this piece of code with a for loop?

Multiple conditions in a while loop

// two conditions
let i = 5, h = 3;
while (i < 10 && h < 50) {
    column(i, -20, h, 'box_pink');
    i++;
    h++;  
}

i (x location) increases from 5 to 9;
h (the column height) increases from 3 to 7.

In this case, i reaches 10 before h can reach 50, so i < 10 limits the loop.

Factorials

We can use a while loop to calculate factorials. Do you remember factorials? For example, 4! = 4 * 3 * 2 * 1

// while loop to calculate factorial of n
function while_fact() {
    let n = prompt('Enter an integer >= 0: ');
    let fact = 1, i = 2;

    while (i <= n) {
        fact *= i;
        i++;
    }  

    column(n, -10, n, 'brick');
    column(n, -12, fact, 'obsidian');
}

// call the function
while_fact()          // enter n as 4

We can also use for loop to calculate factorial:

// for loop to calculate factorial of n  
function for_fact(n) {
    column(-n, -10, n, 'brick');

    let fact = 1;
    for (let i = 2; i < n+1; i++) {
        fact *= i                
    }
    column(-n, -12, fact, 'obsidian');
}

// call the function
for_fact(4)

Run and input the same number for both applications. In this image, you can see that they give the same results: the brick column is n blocks high, and the black column is n! blocks high.