isleward/src/server/items/generators/slots.js

let configSlots = require('../config/slots');
let configTypes = require('../config/types');

let chances = [];
for (let c in configSlots.chance) {
	let rolls = configSlots.chance[c];
	for (let i = 0; i < rolls; i++) 
		chances.push(c);
}

module.exports = {
	generate: function (item, blueprint) {
		if (blueprint.slot)
			item.slot = blueprint.slot;
		else if (blueprint.type)
			item.slot = Object.keys(configTypes.types).find(c => configTypes.types[c][blueprint.type]);
		
		//If the slot doesn't exist or the type doesn't exist in the slot, pick a random type
		if (!item.slot || !configSlots.slots.includes(item.slot))
			item.slot = chances[~~(Math.random() * chances.length)];
	}
};