Sorry, I didn't scale the data!

index.js

// x and y are arrays of -10 to +10 at steps of 0.2,
// f is the function of the answer line,
// targets is a 2d array of all f(x,y)
let x = genNumbers(-10, 10, 0.2);
let y = genNumbers(10, -10, -0.2); // 10 is min and -10 is max so it looks more normal in the array
let f = (x1, x2) => (3 * x1 + 6 * x2 - 24);
// let targets = y.map(y => y.map(x => f(x, y)));


// The random weights and bias, as well as the generated nn-node
let w1 = rand(-10, 10);
let w2 = rand(-10, 10);
let b = rand(-10, 10);
let nn = (x1, x2) => (w1 * x1 + w2 * x2 - b);


console.log(`     w1: ${w1.toFixed(2)},  w2: ${w2.toFixed(2)},  b: ${b.toFixed(2)}`);
console.log(`Targets: 2.00,      1.00,     4.00`);
console.log("");


// find a random point and determine the target and the actual result
let t = [rand(-10, 10).toFixed(2), rand(-10, 10).toFixed(2)];
console.log(` f(${t[0]}, ${t[1]}) = ${f(t[0], t[1])}`);
console.log(`nn(${t[0]}, ${t[1]}) = ${nn(t[0], t[1])}`);


// Calculate the error
let eSquared = Math.pow(f(t[0], t[1]) - nn(t[0], t[1]), 2);
console.log(` e: ${eSquared}`);



// ------------------- COMPARISONS
function sign(x) {
    return Math.sign(x);
}

// ------------------- GENERATE NUMBERS
function genNumbers(min, max, step) {
    step = step || 1;
    let r = [];
    let c = (min, max, i) => min < max ? i <= max : i >= min;
    for (let i = min; c(min, max, i); i += step) r.push(i);
    return r;
}

function numOfRands(min, max, num) {
    let r = [];
    for (let i = 0; i < num; i++) r.push(rand(min, max));
    return r;
}

function rand(min, max) {
    return Math.random() * (max - min) + min;
}