I'm not sure how I can use .toLowerCase() to make my discord command case insensitive this should be simple but I'm really new to this

exports.execute = async (client, message, args) => {
  let userBalance = client.eco.fetchMoney(message.author.id);
  if (userBalance.amount < 1) return message.channel.send("Looks like you don't have the funds for that <:smallsob:922970676283977748>.");
  let item = args[0];
  
  if (!item) return message.channel.send("What do you wish to purchase");

  let hasItem = client.shop[item];
  if (!hasItem || hasItem == undefined) return message.reply("Sorry, that doesn't exist <:smallsob:922970676283977748> Jinn is currently working on this feature so sorry if it's not fully functional");

  let isBalanceEnough = (userBalance.amount >= hasItem.cost);

  if (!isBalanceEnough) return message.reply("Your balance is insufficient. You need <:daisyy:922974700144062474> "+hasItem.cost+" to buy this item.");

  let buy = client.eco.removeMoney(message.author.id, hasItem.cost);
  
  let itemStruct = {
    name: item.toLowerCase(),
    prize: hasItem.cost
  };
  
  client.db.push(`items_${message.author.id}`, itemStruct);
  return message.channel.send(`You purchased **${item}** for **<:daisyy:922974700144062474> ${hasItem.cost}**.`);
};

exports.help = {
  name: "buy",
  aliases: [],
  usage: `buy <item>`
};