Examples

Ready-to-use function examples — order limits, address rules, tag-based restrictions, delivery and payment customizations.

Each example lists the category (which folder to create the function in), the family to pick, and any variables to set. Copy the code into the Functions Console editor, adjust, save and turn the function on.

All money values arrive in the presentment currency — what the buyer sees and pays at checkout. currencyCode is selected once per input; every amount in the same run shares that currency.

Guard nullable objects: buyerIdentity, customer, purchasingCompany, deliveryAddress, metafield, attribute and sellingPlanAllocation are null when absent (e.g. buyerIdentity for anonymous buyers). Reading a property of null throws — and a thrown function fails open, silently skipping your rule for exactly the buyers it targets.

Validation

Order value limit with a configurable threshold

Blocks checkout when the cart total exceeds a limit the merchant can edit on the dashboard — no code changes needed.

Category: Cart and checkout validation · Family: General

Function variables (the Function button in the editor toolbar):

{
  "short_text#MAX_ORDER_TOTAL": "500",
  "metadata": {
    "MAX_ORDER_TOTAL": {
      "subtype": "number",
      "helpText": "Orders above this total are blocked at checkout"
    }
  }
}

Code:

var errors = [];
var limit = parseFloat(vars.MAX_ORDER_TOTAL);

if (limit && parseFloat(input.cart.cost.totalAmount.amount) > limit) {
  errors.push({
    message: 'Orders above ' + vars.MAX_ORDER_TOTAL + ' cannot be completed. Please reduce your order total.',
    target: '$.cart'
  });
}

return errors;

Currency-aware order limit

Applies the limit only when the buyer checks out in a specific currency.

Category: Cart and checkout validation · Family: General

var errors = [];
var total = input.cart.cost.totalAmount;

if (total.currencyCode === 'USD' && parseFloat(total.amount) > 500) {
  errors.push({
    message: 'Orders above $500 USD cannot be completed.',
    target: '$.cart'
  });
}

return errors;

To enforce a limit across all currencies, define per-currency thresholds in a json function variable (e.g. { "USD": 500, "EUR": 450 }) and look up vars.LIMITS[total.currencyCode] in your code.

Block PO boxes in the shipping address

Category: Cart and checkout validation · Family: Address

var errors = [];

(input.cart.deliveryGroups || []).forEach(function (group) {
  var address = group.deliveryAddress;
  if (!address) return;
  var text = ((address.address1 || '') + ' ' + (address.address2 || ''))
    .toLowerCase().replace(/[^a-z]/g, '');
  if (text.indexOf('pobox') > -1 || text.indexOf('postbox') > -1) {
    errors.push({
      message: 'We cannot ship to PO boxes. Please use a street address.',
      target: '$.cart.deliveryGroups[0].deliveryAddress.address1'
    });
  }
});

return errors;

The error appears directly under the address field thanks to the target — see error targets.

Require login to buy gift cards

Category: Cart and checkout validation · Family: General

var errors = [];

var buyer = input.cart.buyerIdentity;

input.cart.lines.forEach(function (line) {
  var product = line.merchandise.product;
  if (product && product.isGiftCard && (!buyer || !buyer.isAuthenticated)) {
    errors.push('Please log in to purchase gift cards.');
  }
});

return errors;

Quantity limit for tagged products

Limits products carrying a specific tag to 2 units per order.

Category: Cart and checkout validation · Family: Product

Query variables (the Query button in the editor toolbar):

{
  "hasProductTags": ["limited"]
}

Code:

var errors = [];

input.cart.lines.forEach(function (line) {
  var product = line.merchandise && line.merchandise.product;
  var isLimited = product && (product.hasTags || []).some(function (t) { return t.hasTag; });
  if (isLimited && line.quantity > 2) {
    errors.push('Maximum 2 units of limited products per order.');
  }
});

return errors;

Wholesale-only bulk orders

Requires a customer tag for quantities above 100.

Category: Cart and checkout validation · Family: Customer

Query variables: { "hasCustomerTags": ["wholesale"] }

var errors = [];
var customer = input.cart.buyerIdentity && input.cart.buyerIdentity.customer;
var isWholesale = customer && (customer.hasTags || []).some(function (t) { return t.hasTag; });

input.cart.lines.forEach(function (line) {
  if (line.quantity > 100 && !isWholesale) {
    errors.push('Quantities above 100 require a wholesale account. Contact us to apply.');
  }
});

return errors;

Delivery customization

Hide express shipping for heavy carts

Category: Delivery customization · Family: General

var ops = [];
var totalWeight = input.cart.lines.reduce(function (sum, line) {
  return sum + (line.merchandise.weight || 0) * line.quantity;
}, 0);

if (totalWeight > 20) {
  input.cart.deliveryGroups.forEach(function (group) {
    group.deliveryOptions.forEach(function (option) {
      if (option.title === 'Express') {
        ops.push({ deliveryOptionHide: { deliveryOptionHandle: option.handle } });
      }
    });
  });
}

return { operations: ops };

Rename a delivery option for loyal customers

Category: Delivery customization · Family: Customer

var ops = [];
var customer = input.cart.buyerIdentity && input.cart.buyerIdentity.customer;

if (customer && customer.numberOfOrders > 10) {
  input.cart.deliveryGroups.forEach(function (group) {
    group.deliveryOptions.forEach(function (option) {
      if (option.title === 'Standard') {
        ops.push({
          deliveryOptionRename: {
            deliveryOptionHandle: option.handle,
            title: 'Standard (free for loyal customers)'
          }
        });
      }
    });
  });
}

return { operations: ops };

Payment customization

Hide Cash on Delivery for B2B buyers

Category: Payment customization · Family: Customer

var ops = [];

if (input.cart.buyerIdentity && input.cart.buyerIdentity.purchasingCompany) {
  input.paymentMethods.forEach(function (method) {
    if (method.name.indexOf('Cash on Delivery') > -1) {
      ops.push({ paymentMethodHide: { paymentMethodId: method.id } });
    }
  });
}

return { operations: ops };

Move a preferred payment method to the top

Category: Payment customization · Family: General

var ops = [];

input.paymentMethods.forEach(function (method) {
  if (method.name === 'Shopify Payments') {
    ops.push({ paymentMethodMove: { paymentMethodId: method.id, index: 0 } });
  }
});

return { operations: ops };

Wallets with logos (Shop Pay, Apple Pay, Google Pay) can be hidden but not renamed or reordered.

Discounts

10% off products with a tag

Category: Discounts · Family: Product

Query variables:

{
  "hasProductTags": ["sale"]
}

Code:

var candidates = [];

input.cart.lines.forEach(function (line) {
  var product = line.merchandise && line.merchandise.product;
  var tagged = product && product.hasTags && product.hasTags.some(function (t) { return t.hasTag; });
  if (tagged) {
    candidates.push({
      message: 'Sale',
      targets: [{ cartLine: { id: line.id } }],
      value: { percentage: { value: 10 } },
    });
  }
});

if (!candidates.length) return { operations: [] };
return { operations: [{ productDiscountsAdd: { selectionStrategy: 'FIRST', candidates: candidates } }] };

Order discount above a threshold

Category: Discounts · Family: General — set MIN_ORDER_TOTAL and ORDER_DISCOUNT_PERCENT as code variables.

var total = parseFloat(input.cart.cost.totalAmount.amount);
var min = parseFloat(vars.MIN_ORDER_TOTAL || '200');
var percent = parseFloat(vars.ORDER_DISCOUNT_PERCENT || '5');

if (total < min) return { operations: [] };

return {
  operations: [{
    orderDiscountsAdd: {
      selectionStrategy: 'FIRST',
      candidates: [{
        message: percent + '% off orders over ' + min,
        targets: [{ orderSubtotal: { excludedCartLineIds: [] } }],
        value: { percentage: { value: percent } },
      }],
    },
  }],
};

The discount function's title is shown to buyers at checkout as the discount name.

Cart transform

Merge tagged products into a bundle

Category: Cart transform · Family: Tags

Query variables:

{
  "hasProductTags": ["bundle"]
}

Code — set BUNDLE_PARENT_VARIANT_ID as a code variable (an existing, published variant that represents the bundle):

var lines = input.cart.lines.filter(function (line) {
  var product = line.merchandise && line.merchandise.product;
  return product && product.hasTags && product.hasTags.some(function (t) { return t.hasTag; });
});

if (lines.length < 2 || !vars.BUNDLE_PARENT_VARIANT_ID) return { operations: [] };

return {
  operations: [{
    linesMerge: {
      cartLines: lines.map(function (l) { return { cartLineId: l.id, quantity: l.quantity }; }),
      parentVariantId: 'gid://shopify/ProductVariant/' + vars.BUNDLE_PARENT_VARIANT_ID,
      title: 'Bundle',
      price: { percentageDecrease: { value: 10 } },
    },
  }],
};

A store can have only one cart transform function, and lineUpdate operations (price/title/image overrides) work on Shopify Plus and development stores only.

Time-based rules

Block checkout outside business hours

Category: Cart and checkout validation · Family: Time

Query variables:

{
  "timeAfter": "09:00:00",
  "timeBefore": "17:00:00"
}

Code:

var errors = [];
var withinHours = input.shop.localTime.timeAfter && input.shop.localTime.timeBefore;

if (!withinHours) {
  errors.push('Orders can only be placed between 9:00 and 17:00. Please come back later.');
}

return errors;

timeAfter / timeBefore arrive as pre-computed booleans against the shop's local time — your code never parses dates. See Families and Variables for the date-time variants.