Develop Reference

How can you add two random variables (with different values) together in Javascript?

This is my code as shown below. My first set is Fibonacci numbers, the second is Lucas Numbers
var f1 = 1;
var f2 = 1;
var f3 = 2;
var f4 = 3;
var f5 = 5;
var f6 = 8;
var f7 = 13;
var f8 = 21;
var f9 = 34;
var f10 = 55;
var f11 = 89;
var f12 = 144;
var l1 = 1;
var l2 = 3;
var l3 = 4;
var l4 = 7;
var l5 = 11;
var l6 = 18;
var l7 = 29;
var l8 = 47;
var l9 = 76;
var l10 = 123;
var l11 = 199;
var l12 = 322;
var num;
var num2;
I have it so that if num = 1, then you add fibonacci, if num = 2, then you add the lucas numbers.
function question(){
num = Math.floor(Math.random() * 2) + 1;
num2 = Math.floor(Math.random() * 2) + 1;
if(num = 1){
document.getElementById("question").innerHTML = "Find the two numbers in the Fibonacci Series which when added together make" + _______ // What goes here?
}
if(num = 2){
document.getElementById("question").innerHTML = "Find the two numbers in the Lucas Series which when added together make" + _______ // What goes here?
}
}
In the blank area, what goes there? I want to put the sum of 2 random variables (as shown above).

To start off, create two arrays holding the numbers as follows :
let fibNums = [1,1,2,3,5,8,13,21,34,55,89,144];
let lucasNums = [1,3,4,7,11,18,29,47,76,123,199,322];
As the next step create a function which can return the sum of two random numbers based on the array
function generateSum(arr, x, y){
console.log(arr[x], arr[y]); // the selected values from the array
return arr[x] + arr[y];
}
Now just call the function with the array name and by generating random index
generateSum(arrayName , Math.floor(Math.random()*arrayName.length), Math.floor(Math.random()*arrayName.length))
Based on your use case
if(num = 1){
generateSum(fibNums , Math.floor(Math.random()*fibNums.length), Math.floor(Math.random()*fibNums.length))
}
if(num = 2){
generateSum(lucasNums , Math.floor(Math.random()*lucasNums.length), Math.floor(Math.random()*lucasNums.length))
}

JavaScript: how to loop by adding the values of variables with 1, 2, 3, ... at the end?

I'm a beginning JavaScript user. I'd like to calculate a score of 15 questions from a program.
What I need:
I put the value I received to JSq1, JSq2, etc. then I add them up and divided by total question and round up a score. I can lay everything in many lines but that does not look efficient. I'm trying to figure out a way to use loop to get all the same result.
Please help.
THANKS
<script language = "JavaScript">
// the following may work
var JSq1 =Varq1score.getValue();
var JSq2 =Varq2score.getValue();
var JSq3 =Varq3score.getValue();
var JSq4 =Varq4score.getValue();
var JSq5 =Varq5score.getValue();
var JSq6 =Varq6score.getValue();
var JSq7 =Varq7score.getValue();
var JSq8 =Varq8score.getValue();
var JSq9 =Varq9score.getValue();
var JSq10 =Varq10score.getValue();
var JSq11 =Varq11score.getValue();
var JSq12 =Varq12score.getValue();
var JSq13 =Varq13score.getValue();
var JSq14 =Varq14score.getValue();
var JSq15 =Varq15score.getValue();
var totalScore = JSq1 + JSq2 + JSq3 + ...
var totalQuestion = 15
var finalScore = parseFloat(totalScore/totalQuestion*100).toFixed(0);
// I'd like to do the following but don't know how to specify JSq1, JSq2, etc in a loop so I don't have to repeat the lines so many times.
var totalQ = 15;
for (i = 0; i <= totalQ ; i++) {
var JSq+[i] = "Varq"+ i + "score.getValue()";
}
for (i = 0; i <= totalQ ; i++) {
var totalScore = totalScore + JSq + [i];
}
...
</script>

1) Build an object all_vars with all the variable. (Here with object shorthand property, { JSq1 } will be equivalent to { JSq1: Varq1score.getValue() }
2) Use Object.values to get values of above object in an array.
3) Use any loop (in this case we are using reduce) to build total score dynamically.
With these slight changes to your current code, you can achieve the result. Check the following sample code.
var JSq1 = 3;
var JSq2 = 3;
var JSq3 = 3;
var JSq4 = 3;
var JSq5 = 3;
var JSq6 = 3;
var JSq7 = 3;
var JSq8 = 3;
var JSq9 = 3;
var JSq10 = 3;
var JSq11 = 3;
var JSq12 = 3;
var JSq13 = 3;
var JSq14 = 3;
var JSq15 = 3;
var all_vars = {
JSq1,
JSq2,
JSq3,
JSq4,
JSq5,
JSq6,
JSq7,
JSq8,
JSq9,
JSq10,
JSq11,
JSq12,
JSq13,
JSq14,
JSq15
};
var totalScore = Object.values(all_vars).reduce((sum, jsq) => sum + jsq, 0);
var totalQuestion = 15;
var finalScore = parseFloat((totalScore / totalQuestion) * 100).toFixed(0);
console.log(finalScore)

Boolean Javascript

Javascript beginner here, I keep getting a wrong answer to this question:
"First, figure out if we have enough slices now. Use a comparison operator to figure out if there are enough. Assign the result to the enoughSlicesNow variable."
//Variables are below//
var cakes = 5;
var slicesPerCake = 6;
var attendees = 60;
var bakers = 3;
var cakeBakingTime = 1;
var hoursLeftUntilParty = 5;
This is what I tried but it will not accept:
(cakes * slicesPerCake)>= attendees
var enoughSlicesNow = false

Looks like you need:
var enoughSlicesNow = (cakes * slicesPerCake) >= attendees;

You can do like this using ternary operator
var cakes = 5;
var slicesPerCake = 6;
var attendees = 60;
var bakers = 3;
var cakeBakingTime = 1;
var hoursLeftUntilParty = 5;
var enoughSlicesNow = (cakes * slicesPerCake) >= attendees ?true:false
alert(enoughSlicesNow)
DEMO

Do you want like this...
var cakes = 5;
var slicesPerCake = 6;
var attendees = 60;
var bakers = 3;
var cakeBakingTime = 1;
var hoursLeftUntilParty = 5;
var enoughSlicesNow = (cakes * slicesPerCake)>= attendees;
if(enoughSlicesNow ==true){
alert('Enough');
}
else
{
alert('Not enough');
}

Failed JS Mandelbrot Set generator outputs odd structure

I made this simple Mandelbrot Set generator in Javascript last night, but it outputs a really strange structure. I think it looks similar to the mandelbrot set, yet oddly deformed. I have no idea why it distorts like this, and I've been trying to find out all day. Does anyone know what causes this or how to fix this?
c = document.getElementById("canvas");
ctx = c.getContext("2d");
c.width = 4000;
c.height = 4000;
declareVariables();
calculateShape();
drawShape();
function declareVariables() {
Re = -2;
Im = -2;
input = [Re,Im];
precision = prompt("input precision (higher is better)");
precision = 1/(precision - precision%4);
segmentAmt = 4/precision;
segmentSize = c.width/segmentAmt;
iterate = prompt("input test amount (higher is better)");
set = [];
for (i=0; i<segmentAmt; i++) {
set[i] = [];
}
numberGrid = [];
for (i=0; i<segmentAmt; i++) {
numberGrid[i] = [];
for (j=0; j<segmentAmt; j++) {
}
}
}
function calculateShape() {
for (i=0; i<segmentAmt; i++) {
input[1] = -2;
input[0] += precision;
for (j=0; j<segmentAmt; j++) {
input[1] += precision;
set[i][j] = 0;
z = [0,0];
for (k=1; k<=iterate; k++) {
store = z;
z[0] = store[0]**2 - store[1]**2 + input[0];
z[1] = 2 * store[0] * store[1] + input[1];
if (z[0]**2 + z[1]**2 > 4) {
set[i][j] = k;
k = iterate+1;
}
}
}
}
}
function drawShape() {
ctx.fillStyle = "white";
ctx.fillRect(0,0,c.width,c.height);
for (i=0; i<segmentAmt; i++) {
for (j=0; j<segmentAmt; j++) {
if (set[i][j] == 0) {
ctx.fillStyle = "black";
} else if (set[i][j] >= 1) {
ctx.fillStyle = 'hsl(' + (25*(set[i][j]-1))**0.75 + ', 100%, 50%)';
}
convertCoords(i,j);
ctx.fillRect(xCoord,yCoord,segmentSize,segmentSize);
}
}
}
function convertCoords(var1,var2) {
xCoord = var1 * segmentSize;
yCoord = var2 * segmentSize;
}
Output image:

The error appears to be on this line in calculateShape():
store = z;
It seems you want store to be a copy of z, but this just ends up with store and z referring to the same array. The next line calculates z[0], but as store and z refer to the same array, store[0] has the new value of z[0] rather than the previous. Hence the calculation of z[1] in the line after that is incorrect.
Replace the above line with either
store = [z[0], z[1]];
or
store = z.slice();
Both of these lines ensure that store refers to a different array to z, so when you recalculate z[0], store[0] is unaffected.

I want to add all the values in the field Sum to the field Total but it is not working

Here, sums[i].value is getting right values but when I want to keep a grand total of all Sum, it is failing.
function calc() {
var amounts = document.getElementsByName("Amount");
var prices = document.getElementsByName("Price");
var sums = document.getElementsByName('Sum');
var tax = document.getElementsByName('Tax');
var total = document.getElementsByName('Total');
for (var i = 0; i < amounts.length; i++) {
sums[i].value = amounts[i].value * prices[i].value;
total[0].value = total[0].value + sums[i].value;
// only this line is not working
}
}

Plain HTML is strings, all the way down, and var amounts = document.getElementsByName("Amount"); followed by amounts.value means you now have string values. Since + is also a string operator, JavaScript will happily turn "2"+"4" into "24", which looks like it did maths, but wrong, when in fact it didn't do math at all.
Convert all values that need to be numbers into numbers, first:
var amounts = document.getElementsByName("Amount");
....
var amount = parseFloat(amounts.value); // NOW it's a number
...

Replace your code with :
for (var i = 0; i < amounts.length; i++) {
sums[i].value = parseFloat(amounts[i].value) * parseFloat(prices[i].value);
total[0].value = parseFloat(total[0].value) + parseFloat(sums[i].value);
// only this line is not working
}

sums[i].value = parseFloat(amounts[i].value) * parseFloat(prices[i].value);
total[0].value = parseFloat(total[0].value) + parseFloat(sums[i].value);
This should help you.

Remove the .value while adding and multiplying
function test()
{
var amounts = new Array();
amounts[0] = "4";
amounts[1] = "6";
amounts[2] = "10";
var prices = new Array();
prices[0] = "4";
prices[1] = "6";
prices[2] = "10";
var sums = new Array();
var total = 0;
for (var i = 0; i < amounts.length; i++) {
sums[i] = parseInt(amounts[i]) * parseInt(prices[i]);
total= parseInt(total) + parseInt(sums[i]);
// only this line is not working
//alert(total); is 152
}
}