Checkjebon.nl javascript library

Checkjebon.nl makes comparing food prices across multiple supermarkets easy. With this library, you can programmatically query supermarket prices, compare shopping lists, and analyze product data using the same algorithms as the Checkjebon.nl website.

Features

• Compare prices for products across multiple supermarkets
• Optimize shopping across multiple stores to minimize total cost
• Get list of available supermarkets
• Fuzzy product search and best-match selection
• Support for generic and brand-specific queries
• Price estimation when no direct match is found
• Generate Checkjebon.nl links for shopping lists

API Reference

getPricesForProducts(productNames)

Get price information for a list of products across all available supermarkets.

Parameters:

• productNames (string[]): Array of product names to search for

Returns: Promise<Array>

• Array of supermarket objects, each containing:
  • code (string): Supermarket code (e.g., "ah", "jumbo")
  • name (string): Supermarket display name
  • icon (string|null): URL to supermarket icon
  • totalProducts (number): Total products available at this supermarket
  • products (Array): Array of product objects with:
    • name (string|null): Product name
    • link (string|null): Link to product page
    • price (number|null): Price in euros
    • amount (string|null): Product size/amount
    • isEstimate (boolean): Whether price is estimated
    • originalQuery (string): Original search query

Example:

const products = await getPricesForProducts([
  "1,5 liter halfvolle melk",
  "250 gram roomboter",
  "6 eieren"
]);

for (const supermarket of products) {
  console.log(`${supermarket.name}: €${supermarket.products[0].price}`);
}

getOptimalShoppingPlan(productNames, maxSupermarketVisitCount, selectedSupermarketCodes)

Find the optimal combination of supermarkets to buy products from, minimizing total cost while respecting the maximum number of stores you want to visit.

Parameters:

• productNames (string[]): Array of product names to buy
• maxSupermarketVisitCount (number): Maximum number of supermarkets to visit
• selectedSupermarketCodes (string[]): Array of supermarket codes to choose from (e.g., ["ah", "jumbo", "lidl"])

Returns: Promise<Object>

• Object containing:
  • totalCost (number): Total cost in euros for all products
  • supermarkets (Array): Array of selected supermarket objects with:
    • code (string): Supermarket code
    • name (string): Supermarket name
    • icon (string|null): Supermarket icon URL
    • products (Array): Products to buy at this supermarket

Example:

const result = await getOptimalShoppingPlan(
  ["melk", "brood", "kaas"],
  3, // Visit maximum 3 stores
  ["ah", "dirk", "jumbo", "vomar", "lidl", "aldi"]
);

console.log(`Total cost: €${result.totalCost}`);
console.log(`Stores to visit: ${result.supermarkets.length}`);

for (const store of result.supermarkets) {
  console.log(`\nBuy at ${store.name}:`);
  for (const product of store.products) {
    console.log(`  - ${product.name}: €${product.price}`);
  }
}

getSupermarkets()

Get a list of all available supermarkets with their codes, names, and icons.

Returns: Promise<Array>

• Array of supermarket objects with:
  • code (string): Supermarket code (e.g., "ah", "jumbo")
  • name (string): Full supermarket name
  • icon (string|null): URL to supermarket icon

Example:

const supermarkets = await getSupermarkets();

console.log("Available supermarkets:");
for (const store of supermarkets) {
  console.log(`${store.code}: ${store.name}`);
}

getCheckjebonLink(shoppingList)

Generate a Checkjebon.nl URL with a pre-filled shopping list.

Parameters:

• shoppingList (string|string[]): Shopping list as a string (one item per line) or array of items

Returns: string

• URL to open on Checkjebon.nl with the shopping list

Example:

const url = getCheckjebonLink([
  "melk",
  "brood",
  "kaas"
]);
console.log(url);
// Opens: https://www.checkjebon.nl/#melk%0Abrood%0Akaas

pricesLastUpdated()

Get the timestamp when price data was last updated.

Returns: Date|null

• Date object representing when prices were last fetched, or null if not available

Example:

const lastUpdate = pricesLastUpdated();
if (lastUpdate) {
  console.log(`Prices last updated: ${lastUpdate.toLocaleString()}`);
} else {
  console.log('Prices last updated: Unknown');
}

How It Works

For each product in your shopping list, the library:

1. Attempts an exact match by name.
2. If no exact match, performs a fuzzy search (matches all letters in order, not necessarily adjacent).
3. Filters by amount (liter/kilogram) if specified.
4. Orders results by string match quality, then by price.
5. Returns the best match for each supermarket.
6. If no price is found, estimates based on averages from other supermarkets.

Example Usage

Basic Price Comparison

const cjb = require('./checkjebon');

const shoppingList = [
  "1,5 liter halfvolle melk",
  "250 gram roomboter",
  "1 liter cola"
];

cjb.getPricesForProducts(shoppingList).then(result => {
  console.log(JSON.stringify(result, null, 2));

  const link = cjb.getCheckjebonLink(shoppingList);
  console.log(link);

  const lastUpdate = cjb.pricesLastUpdated();
  console.log(lastUpdate);
});

Multi-Supermarket Shopping Optimizer

const cjb = require('./checkjebon');

const products = [
  "1,5 liter halfvolle melk",
  "250 gram roomboter",
  "6 eieren",
  "1 kilo bananen"
];

// Get list of available supermarkets
cjb.getSupermarkets().then(supermarkets => {
  console.log("Available supermarkets:");
  supermarkets.forEach(s => console.log(`  ${s.code}: ${s.name}`));
});

// Optimize shopping across multiple stores
const maxStores = 3;
const selectedStores = ["ah", "dirk", "jumbo", "vomar", "lidl", "aldi"];

cjb.getOptimalShoppingPlan(products, maxStores, selectedStores)
  .then(result => {
    console.log(`Total Cost: €${result.totalCost.toFixed(2)}`);
    console.log(`Stores to Visit: ${result.supermarkets.length}\n`);
    
    result.supermarkets.forEach(store => {
      console.log(`${store.name}:`);
      store.products.forEach(p => {
        console.log(`  - ${p.name}: €${p.price.toFixed(2)}`);
      });
    });
  });

Running the Examples

There are two example files provided:

• example.node.js: Run this example in Node.js to see how to use the library programmatically.
• example.browser.html: Open this file in your web browser to see a browser-based example.

Run the Node.js Example

node example.node.js

Open the Browser Example

Simply open example.browser.html in your web browser (double-click or right-click and choose "Open with" > your browser).

Running Tests

This project uses Mocha for testing. To run the tests, use:

node test

Product Selection Algorithm

• Exact match by name
• Fuzzy search if no exact match
• Filter by amount if specified
• Order by string match quality, then price
• Return best match per supermarket

Open Data

Product price data is updated frequently and can be reused in other projects (e.g., price alerts, trend analysis, data journalism).

License

MIT

More Information

Visit Checkjebon.nl for more details and to use the web interface.