Build a Card Price Tracker

const API_BASE = "https://api.tcgapi.dev/v1";
const API_KEY = "tcg_live_your_key_here";

// Search for a card across all games
async function checkPriceAlert(cardName, thresholdPercent = 10) {
  const headers = { "X-API-Key": API_KEY };

  // Step 1: Search for the card
  const searchRes = await fetch(
    `${API_BASE}/search?q=${encodeURIComponent(cardName)}&game=pokemon&limit=1`,
    { headers }
  );
  const { results } = await searchRes.json();

  if (!results || results.length === 0) {
    console.log(`No results found for "${cardName}"`);
    return null;
  }

  const card = results[0];

  // Step 2: Get current price data with change metrics
  const priceRes = await fetch(
    `${API_BASE}/cards/${card.id}/prices`,
    { headers }
  );
  const priceData = await priceRes.json();

  // Step 3: Check if 24h change exceeds threshold
  const change24h = priceData.change_24h || 0;
  const alert = Math.abs(change24h) >= thresholdPercent;

  return {
    name: card.name,
    set: card.set_name,
    market_price: priceData.market_price,
    change_24h: change24h,
    change_7d: priceData.change_7d,
    alert: alert,
    direction: change24h > 0 ? "UP" : "DOWN"
  };
}

// Track a watchlist of cards
const watchlist = ["Charizard ex", "Pikachu VMAX", "Moonbraker"];

for (const card of watchlist) {
  const result = await checkPriceAlert(card, 5);
  if (result?.alert) {
    console.log(
      `ALERT: ${result.name} (${result.set}) is ${result.direction} ` +
      `${result.change_24h.toFixed(1)}% — now $${result.market_price.toFixed(2)}`
    );
  }
}

// Get the top gainers and losers for Pokemon
const res = await fetch(
  `${API_BASE}/prices/top-movers?game=pokemon&period=24h&limit=10`,
  { headers: { "X-API-Key": API_KEY } }
);
const { gainers, losers } = await res.json();

console.log("Top 10 Pokemon Gainers (24h):");
gainers.forEach(card => {
  console.log(`  +${card.change_pct.toFixed(1)}%  ${card.name} — $${card.market_price.toFixed(2)}`);
});