Array in JavaScript is undefined

Question

I am very new to JavaScript but have good experience with C and java. For whatever reason my code below will not fill in the array with values other than undefined. I'm trying to simply fill an array with a random set of numbers for a blackjack game

let randomSuite;
let randomNum
let count = 0;
var cards = new Array(56);
window.onload = function main(){
const suites = [
    "H",
    "D",
    "S",
    "C"
];

for(let i = 0 ; i < 56 ; i++){
    randomNum = (Math.random * 12) + 1;
    randomSuite = Math.random * 3;
    cards.push = randomNum;
    console.log(cards[i]);
    count++;
}
alert(cards[1]);
}
function hitFunc(){
    alert("works " + cards[0]);
}

*{
    margin: 0;
    padding : 0;
    font-family: sans-serif;
}

.main{
    width: 100%;
    height: 100vh;
    background-color:black;
}

.img1{
    position: relative;
    z-index: -1;
    margin: 10px auto 20px;
    display: block;
    width: 75%;
    height: 75%;
}

.img2{
    position: relative;
    z-index: 1;
    margin: 10px auto 20px;
    display: block;
    bottom: 200px;
    right: 400px;
    width: 7%;
    height: 7%;
}

.hitButton {
z-index: 1;
position: relative;
text-align: center;
left: 225px;
bottom: 550px;
}

.center {
    display: block;
    margin-left: auto;
    margin-right: auto;
    width: 50%;
    color: aliceblue;
    object-position: center;
  }

Here's what I have. The alerts are used to show that the function is being completed. Any help is appreciated Please leave an explanation as well. This is my first post on stack overflow let me know if there's anyway to improve the quality of my post.

Answer 1

Call functions with parenthesis

Math.random() and push() are functions not variables therefore you need to call them using ().

push() will append to the array

push() will append a value to the array. You already initialize an array with 10 values. Pushing new values will increase the array size but not add values in the first 10 spots.

const array = new Array(10);

for(let i = 0; i < 10; i++){
  array.push(i);
}
console.log(array);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Solution

You should instead use array[i] = value; to set a value on a given position.

const array = new Array(10);

for(let i = 0; i < 10; i++){
  array[i] = i;
}
console.log(array);

.as-console-wrapper { max-height: 100% !important; top: 0; }

If you want to have a more functional way of doing this as is typical for JavaScript you could use map():

const array = [...new Array(10)].map((_, index) => index);
console.log(array);

.as-console-wrapper { max-height: 100% !important; top: 0; }