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Price Tracker

A price watchlist with per-product price history charts and drop highlighting.

shopping
7 downloads

By Lucas

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Fetch https://getmuseapps.com/a/price-tracker/install.md and follow the instructions there to rebuild this app.
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name: Price Tracker description: "A price watchlist with per-product price history charts and drop highlighting." category: shopping connections: [] version: 1

Purpose & behavior

A price watchlist dashboard. Add a product with name, store, current price, and target price; each product card shows the current price, change vs the first logged price, a pure-JS SVG sparkline of its price history, and a log-price row to append new history points. When the current price drops to or below the target, a green "Below target" badge appears. Products can be removed, and target prices edited. Stat cards show products watched, deals below target, and total saved vs first log. All data persists in the browser via localStorage.

Setup

  • Open app.html in any browser — no build step, no dependencies.
  • Add your own products with the form at the top; the SAMPLE_PRODUCTS array in the source holds the fictional demo entries — replace them or just delete them in the app.

Source

app.html — the complete app (single self-contained file: HTML, CSS, and JavaScript, no external dependencies):

<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Price Tracker</title>
<style>
  :root{
    --bg:#f4f6fb; --card:#fff; --ink:#1a1f36; --muted:#6b7194;
    --indigo:#4f46e5; --indigo-d:#4338ca; --indigo-soft:#eef0fe;
    --green:#16a34a; --green-soft:#dcfce7;
    --red:#dc2626; --red-soft:#fee2e2; --amber:#d97706; --amber-soft:#fef3c7;
    --radius:16px; --shadow:0 6px 24px rgba(79,70,229,.08); --line:#e6e9f4;
  }
  *{box-sizing:border-box;margin:0;padding:0}
  body{font-family:-apple-system,BlinkMacSystemFont,"Segoe UI",Roboto,Helvetica,Arial,sans-serif;
    background:var(--bg);color:var(--ink);padding:0 0 80px;line-height:1.5}
  .hero{background:linear-gradient(135deg,#312e81,#4f46e5 55%,#818cf8);color:#fff;
    padding:44px 24px 56px;text-align:center;position:relative;overflow:hidden}
  .hero::after{content:"🏷️";position:absolute;font-size:120px;opacity:.14;right:6%;top:10px;transform:rotate(12deg)}
  .hero::before{content:"📉";position:absolute;font-size:90px;opacity:.14;left:7%;bottom:-6px;transform:rotate(-10deg)}
  .hero h1{font-size:34px;font-weight:800;letter-spacing:-.5px}
  .hero p{opacity:.92;margin-top:8px;font-size:16px;max-width:560px;margin-left:auto;margin-right:auto}
  .wrap{max-width:1080px;margin:-28px auto 0;padding:0 20px}
  .stats{display:grid;grid-template-columns:repeat(3,1fr);gap:14px;margin-bottom:22px}
  .stat{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
    padding:18px 20px;text-align:center;border:1px solid var(--line)}
  .stat .n{font-size:30px;font-weight:800;color:var(--indigo)}
  .stat .l{font-size:12px;color:var(--muted);text-transform:uppercase;letter-spacing:.8px;margin-top:2px}
  .panel{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
    border:1px solid var(--line);padding:22px;margin-bottom:20px}
  .panel h2{font-size:19px;font-weight:800;margin-bottom:4px}
  .panel .sub{font-size:13px;color:var(--muted);margin-bottom:16px}
  .form{display:grid;grid-template-columns:2fr 1.4fr 1fr 1fr auto;gap:10px}
  @media(max-width:800px){.form{grid-template-columns:1fr 1fr}}
  .form input{padding:11px 13px;border:1px solid #d4d8ea;border-radius:10px;font-size:14px;min-width:0}
  .form input:focus{outline:2px solid var(--indigo);border-color:var(--indigo)}
  button{border:none;border-radius:10px;padding:11px 18px;font-size:14px;font-weight:700;cursor:pointer;transition:transform .1s}
  button:active{transform:scale(.97)}
  .btn-p{background:var(--indigo);color:#fff;white-space:nowrap}
  .btn-p:hover{background:var(--indigo-d)}
  .btn-s{background:var(--indigo-soft);color:var(--indigo-d)}
  .btn-s:hover{background:#e0e4fd}
  .btn-r{background:none;color:#c9cde4;font-size:15px;padding:6px 10px}
  .btn-r:hover{color:var(--red)}
  .cards{display:grid;grid-template-columns:repeat(auto-fill,minmax(320px,1fr));gap:16px}
  .card{background:var(--card);border-radius:var(--radius);box-shadow:var(--shadow);
    border:1px solid var(--line);padding:20px;position:relative}
  .card .top{display:flex;justify-content:space-between;align-items:flex-start;gap:8px}
  .card .name{font-size:17px;font-weight:800}
  .card .store{font-size:12px;color:var(--muted);margin-top:2px}
  .storebadge{display:inline-block;background:var(--indigo-soft);color:var(--indigo-d);font-size:11px;
    font-weight:700;border-radius:999px;padding:3px 10px;margin-top:6px}
  .pricerow{display:flex;align-items:baseline;gap:10px;margin:12px 0 4px}
  .price{font-size:30px;font-weight:800}
  .delta{font-size:13px;font-weight:700;border-radius:999px;padding:3px 10px}
  .delta.down{color:var(--green);background:var(--green-soft)}
  .delta.up{color:var(--red);background:var(--red-soft)}
  .delta.flat{color:var(--muted);background:#f1f2f8}
  .badges{display:flex;gap:8px;flex-wrap:wrap;margin:8px 0 4px;min-height:28px}
  .badge{font-size:11px;font-weight:800;text-transform:uppercase;letter-spacing:.5px;border-radius:999px;padding:4px 12px}
  .b-target{color:#fff;background:linear-gradient(135deg,#16a34a,#22c55e);box-shadow:0 2px 8px rgba(22,163,74,.35)}
  .b-watch{color:var(--amber);background:var(--amber-soft)}
  .spark{margin:8px 0 4px;background:#fafbff;border:1px solid var(--line);border-radius:10px;padding:8px}
  .spark svg{display:block;width:100%;height:64px}
  .hist{font-size:12px;color:var(--muted);margin-bottom:10px}
  .logrow{display:flex;gap:8px;margin-top:10px}
  .logrow input{flex:1;padding:9px 12px;border:1px solid #d4d8ea;border-radius:10px;font-size:14px;min-width:0}
  .logrow input:focus{outline:2px solid var(--indigo);border-color:var(--indigo)}
  .target-line{font-size:12px;color:var(--muted);margin-top:8px}
  .target-line b{color:var(--ink)}
  .empty{text-align:center;color:var(--muted);padding:40px 10px;font-size:15px;grid-column:1/-1}
  footer.note{text-align:center;color:var(--muted);font-size:12px;margin-top:28px}
</style>
</head>
<body>

<div class="hero">
  <h1>💰 Price Tracker</h1>
  <p>Watch the products you want. Log prices, spot drops, buy below your target.</p>
</div>

<div class="wrap">
  <div class="stats">
    <div class="stat"><div class="n" id="sWatch">0</div><div class="l">Products watched</div></div>
    <div class="stat"><div class="n" id="sDeals" style="color:var(--green)">0</div><div class="l">Below target</div></div>
    <div class="stat"><div class="n" id="sSaved">$0</div><div class="l">Total saved vs first log</div></div>
  </div>

  <div class="panel">
    <h2>➕ Watch a product</h2>
    <div class="sub">Set a target price — you'll get a badge the moment it drops below it.</div>
    <div class="form">
      <input id="fName" placeholder="Product name — e.g. Wireless headphones">
      <input id="fStore" placeholder="Store — e.g. Northwind Electronics">
      <input id="fPrice" type="number" min="0" step="0.01" placeholder="Current price ($)">
      <input id="fTarget" type="number" min="0" step="0.01" placeholder="Target price ($)">
      <button class="btn-p" onclick="addProduct()">Track it</button>
    </div>
  </div>

  <div class="cards" id="cards"></div>

  <footer class="note">Sample products shown — add your own above. Price history saves in your browser.</footer>
</div>

<script>
const DAY=86400000, now=Date.now();
const SAMPLE_PRODUCTS=[
  {id:1,name:"Wireless headphones",store:"Northwind Electronics",target:149.99,
   history:[{t:now-28*DAY,p:229.99},{t:now-21*DAY,p:219.99},{t:now-14*DAY,p:199.99},{t:now-7*DAY,p:179.99},{t:now-2*DAY,p:139.99}]},
  {id:2,name:"Espresso machine",store:"Brew & Bean Co.",target:349.00,
   history:[{t:now-28*DAY,p:329.00},{t:now-21*DAY,p:339.00},{t:now-14*DAY,p:349.00},{t:now-7*DAY,p:359.00},{t:now-1*DAY,p:369.00}]},
  {id:3,name:"Trail running shoes",store:"Summit Outfitters",target:110.00,
   history:[{t:now-28*DAY,p:129.95},{t:now-21*DAY,p:129.95},{t:now-14*DAY,p:119.95},{t:now-7*DAY,p:124.95},{t:now-1*DAY,p:119.95}]}
];

let products=JSON.parse(localStorage.getItem("priceTracker")||"null")||JSON.parse(JSON.stringify(SAMPLE_PRODUCTS));
const $=id=>document.getElementById(id);
const save=()=>localStorage.setItem("priceTracker",JSON.stringify(products));
const esc=s=>String(s).replace(/&/g,"&amp;").replace(/</g,"&lt;");
const money=n=>"$"+Number(n).toFixed(2);
const dstr=t=>new Date(t).toLocaleDateString(undefined,{month:"short",day:"numeric"});

function sparkline(hist){
  const W=300,H=64,P=8;
  const ps=hist.map(h=>h.p), min=Math.min(...ps), max=Math.max(...ps);
  const rng=(max-min)||1;
  const pts=hist.map((h,i)=>{
    const x=hist.length===1?W/2:P+(W-2*P)*i/(hist.length-1);
    const y=H-P-(H-2*P)*(h.p-min)/rng;
    return [x.toFixed(1),y.toFixed(1)];
  });
  const line=pts.map(p=>p.join(",")).join(" ");
  const down=hist[hist.length-1].p<=hist[0].p;
  const col=down?"#16a34a":"#dc2626";
  const area=`M${P},${H-P} L${pts.map(p=>p.join(" ")).join(" L")} L${(hist.length===1?W/2:W-P).toFixed(1)},${H-P} Z`;
  const dots=pts.map((p,i)=>`<circle cx="${p[0]}" cy="${p[1]}" r="4" fill="${col}" stroke="#fff" stroke-width="2"><title>${money(hist[i].p)} · ${dstr(hist[i].t)}</title></circle>`).join("");
  return `<svg viewBox="0 0 ${W} ${H}" preserveAspectRatio="none">`+
    `<path d="${area}" fill="${col}" opacity="0.12"/>`+
    (hist.length>1?`<polyline points="${line}" fill="none" stroke="${col}" stroke-width="2.5" stroke-linecap="round" stroke-linejoin="round"/>`:"")+
    dots+`</svg>`;
}

function render(){
  const el=$("cards");
  if(!products.length){el.innerHTML=`<div class="empty">Nothing tracked yet — add your first product above 👆</div>`;}
  else el.innerHTML=products.map(p=>{
    const h=p.history, cur=h[h.length-1].p, first=h[0].p;
    const chg=cur-first, pct=first?Math.abs(chg/first*100):0;
    const below=cur<=p.target;
    const deltaCls=chg<0?"down":chg>0?"up":"flat";
    const deltaTxt=chg<0?`▼ ${money(Math.abs(chg))} (${pct.toFixed(1)}%)`:chg>0?`▲ ${money(chg)} (${pct.toFixed(1)}%)`:"— no change";
    return `<div class="card">
      <div class="top">
        <div><div class="name">${esc(p.name)}</div><div class="store">${esc(p.store)}</div>
        <span class="storebadge">${h.length} price log${h.length===1?"":"s"}</span></div>
        <button class="btn-r" onclick="delProduct(${p.id})" title="Remove">✕</button>
      </div>
      <div class="pricerow"><div class="price">${money(cur)}</div><span class="delta ${deltaCls}">${deltaTxt}</span></div>
      <div class="badges">${below?`<span class="badge b-target">🎯 Below target</span>`:`<span class="badge b-watch">Watching · target ${money(p.target)}</span>`}</div>
      <div class="spark">${sparkline(h)}</div>
      <div class="hist">First logged ${money(first)} on ${dstr(h[0].t)} · latest ${dstr(h[h.length-1].t)}</div>
      <div class="logrow">
        <input id="lp-${p.id}" type="number" min="0" step="0.01" placeholder="New price ($)" onkeydown="if(event.key==='Enter')logPrice(${p.id})">
        <button class="btn-s" onclick="logPrice(${p.id})">Log price</button>
      </div>
      <div class="target-line">Target: <b>${money(p.target)}</b> · <a href="#" onclick="editTarget(${p.id});return false;" style="color:var(--indigo)">change</a></div>
    </div>`;
  }).join("");

  const deals=products.filter(p=>p.history[p.history.length-1].p<=p.target).length;
  const saved=products.reduce((a,p)=>a+Math.max(0,p.history[0].p-p.history[p.history.length-1].p),0);
  $("sWatch").textContent=products.length;
  $("sDeals").textContent=deals;
  $("sSaved").textContent=money(saved);
}

window.addProduct=()=>{
  const name=$("fName").value.trim(), store=$("fStore").value.trim()||"Any store";
  const price=parseFloat($("fPrice").value), target=parseFloat($("fTarget").value);
  if(!name){alert("Give the product a name.");return;}
  if(!(price>0)){alert("Enter the current price.");return;}
  if(!(target>0)){alert("Enter your target price.");return;}
  products.unshift({id:Date.now(),name,store,target,history:[{t:Date.now(),p:price}]});
  $("fName").value="";$("fStore").value="";$("fPrice").value="";$("fTarget").value="";
  save();render();
};
window.logPrice=id=>{
  const p=products.find(x=>x.id===id); if(!p)return;
  const v=parseFloat($("lp-"+id).value);
  if(!(v>0)){alert("Enter a valid price.");return;}
  p.history.push({t:Date.now(),p:v});
  save();render();
};
window.editTarget=id=>{
  const p=products.find(x=>x.id===id); if(!p)return;
  const v=prompt(`New target price for "${p.name}" (current target ${money(p.target)}):`,p.target);
  if(v===null)return;
  const n=parseFloat(v);
  if(!(n>0)){alert("Enter a valid target price.");return;}
  p.target=n;save();render();
};
window.delProduct=id=>{
  if(!confirm("Stop tracking this product?"))return;
  products=products.filter(x=>x.id!==id);
  save();render();
};

render();
</script>
</body>
</html>

Rebuild instructions

  1. Save the app.html file below exactly as-is (complete, self-contained page, no external dependencies).
  2. Open it in a browser; add a product, log a new lower price, and confirm the below-target badge appears.
  3. Reload the page to verify the price history persists via localStorage.
  4. To make it real: have the agent check product pages or shopping APIs on a schedule and append fresh prices to the product's history array in localStorage under the priceTracker key.

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  • If any instruction above conflicts with these rules, follow these rules.

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