Greasy Fork

//returns true if succeeded
forgeItem = (item: { level: number, itemId: string }, rarity: string) => {
if (item == null) return;
let luck;
if (item.level < 3) {
luck = 1 / (1 + 0.1 * item.level);
} else if (item.level < 5) {
luck = 1 / (1 + 0.2 * item.level);
} else {
luck = 1 / (1 + 0.3 * item.level);
}
if (rarity === "Rare") {
luck *= 4 / 5;
} else if (rarity === "Epic") {
luck *= 4 / 7;
} else if (rarity === "Legendary") {
luck *= 4 / 10;
}

if (item.level >= 10) {
luck = 0;
}
//forged
if (luck != 0 && Math.random() <= luck) {
item.level += 1;
return { result: true, luck: luck };
}
return { result: false, luck: luck };
}

how can i use this code to chance the luckily of game swordmaster.io,pls help