> ## Documentation Index
> Fetch the complete documentation index at: https://docs.elasticfunnels.io/llms.txt
> Use this file to discover all available pages before exploring further.

# Functions

> formatPrice, cartCount, cartSubtotal, lineTotal, and string helpers. When to use formatPrice vs pre-formatted values.

Expressions in **`[[ ... ]]`**, **`data-condition`**, **`data-ef-text`**, and similar attributes can call **built-in functions**. You can also **register** custom functions with **`registerTemplateFunction(name, fn)`** or **`registerTemplateFunctions({ name: fn, ... })`**.

***

## Price display: when to use `formatPrice` vs as-is

Most **checkout** and **cart** values are **already formatted** (e.g. `"$29.00"`). Use them directly in **`[[ ... ]]`**. Use **`formatPrice()`** only when you need to display a **raw number** (e.g. **`*_raw`** keys or a computed number).

<Tabs>
  <Tab title="Use as-is (no formatPrice)">
    These are **pre-formatted**. Use **`[[ variable ]]`** only.

    | Variable            | Example                                                                                                                                                                                                                                                          |
    | ------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
    | **Checkout totals** | `checkout.product_price`, `checkout.retail_price`, `checkout.bump_total`, `checkout.subtotal_before_discount`, `checkout.discount_total`, `checkout.subtotal_after_discount`, `checkout.subtotal` (alias), `checkout.shipping`, `checkout.tax`, `checkout.total` |
    | **Cart item**       | `item.price`, `item.total`, `item.retail_price`, `item.discount_total`                                                                                                                                                                                           |
    | **Bump / line**     | `bump.price`, `line.price`                                                                                                                                                                                                                                       |

    **In template:** `[[ checkout.total ]]`, `[[ item.price ]]`, `[[ bump.price ]]`
  </Tab>

  <Tab title="Use formatPrice (raw numbers)">
    Use **`formatPrice(value, currency?)`** when displaying a **numeric** value that has no formatted key, or when you explicitly use a **`_raw`** key.

    | When                    | Example                                                                                                                                                                                                                                                                                                                                                                           |
    | ----------------------- | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
    | **Checkout \_raw keys** | `formatPrice(checkout.total_raw, checkout.currency)` — only if you must show a raw number; normally use formatted keys (`checkout.total`, etc.). Raw keys include `product_price_raw`, `retail_price_raw`, `bump_total_raw`, `subtotal_before_discount_raw`, `discount_total_raw`, `subtotal_after_discount_raw`, `subtotal_raw` (alias), `shipping_raw`, `tax_raw`, `total_raw`. |
    | **Bump/line raw**       | `formatPrice(bump.price_raw, checkout.currency)` — for display of raw; normal display use `[[ bump.price ]]`.                                                                                                                                                                                                                                                                     |
    | **Computed value**      | `formatPrice(lineTotal(item), currency)` — when `item.total` is not provided.                                                                                                                                                                                                                                                                                                     |
  </Tab>
</Tabs>

<Warning>
  Do **not** pass an already-formatted string into **formatPrice** (e.g. `formatPrice(checkout.total, ...)` or `formatPrice(item.price, ...)`). That can produce wrong or duplicated currency symbols.
</Warning>

***

## `formatPrice(value, currency?, locale?)` / `money` / `formatCurrency`

Formats a **numeric** value as currency.

| Parameter    | Description                                                                                               |
| ------------ | --------------------------------------------------------------------------------------------------------- |
| **value**    | Number (or parseable to number)                                                                           |
| **currency** | Optional. Code (e.g. `USD`) or symbol. If omitted, uses `checkout.currency` or `scope.currency` or `USD`. |
| **locale**   | Optional. For `Intl.NumberFormat`.                                                                        |

***

## Cart helpers

| Function                                                                      | Returns                                                           | Example                                                                          |
| ----------------------------------------------------------------------------- | ----------------------------------------------------------------- | -------------------------------------------------------------------------------- |
| **`lineTotal(item, quantityKey?, priceKey?)`**                                | quantity × price for one item (default keys: `quantity`, `price`) | `[[ formatPrice(lineTotal(item), currency) ]]` when `item.total` is not in scope |
| **`cartCount(items)`** / **`cart_count(items)`**                              | Sum of item quantities                                            | `[[ cartCount(cartItems) ]]`                                                     |
| **`cartSubtotal(items, quantityKey?, priceKey?)`** / **`cart_subtotal(...)`** | Numeric sum of line totals                                        | `[[ formatPrice(cartSubtotal(cartItems), checkout.currency) ]]`                  |

***

## String helpers

All coerce to string; `null`/`undefined` become empty string.

| Function                      | Description               | Example result  |
| ----------------------------- | ------------------------- | --------------- |
| **`upper`** / **`uppercase`** | Uppercase                 | "ALPHA"         |
| **`lower`** / **`lowercase`** | Lowercase                 | "alpha"         |
| **`capitalize`**              | First character uppercase | "Alpha"         |
| **`titleCase`** / **`title`** | Title case                | "Product Alpha" |
| **`camelCase`** / **`camel`** | camelCase                 | "someLabel"     |
| **`snakeCase`** / **`snake`** | snake\_case               | "some\_label"   |
| **`kebabCase`** / **`kebab`** | kebab-case                | "some-label"    |

***

## Custom functions

Register from application or plugin code:

```javascript theme={null}
import { registerTemplateFunction, registerTemplateFunctions } from './utils/templateProcessor.js';

registerTemplateFunction('myFormat', (value) => {
  return value != null ? String(value).toUpperCase() : '';
});

registerTemplateFunctions({
  double: (n) => Number(n) * 2,
  greet: (name) => `Hello, ${name || 'Guest'}!`
});
```

Then in templates: **`[[ myFormat(item.name) ]]`**, **`[[ double(item.quantity) ]]`**, **`[[ greet(checkout.customer.first_name) ]]`**.

***

## Summary

* **Price display:** Use the [table above](#price-display-when-to-use-formatprice-vs-as-is): pre-formatted keys as-is; **formatPrice** only for **raw** values or computed numbers.
* **Cart:** **`cartCount`**, **`cartSubtotal`**, **`lineTotal`**; combine with **formatPrice** when you need a formatted string from a number.
* **Strings:** **`upper`**, **`lower`**, **`capitalize`**, **`titleCase`**, **`camelCase`**, **`snakeCase`**, **`kebabCase`** (and aliases).
* **Custom:** **`registerTemplateFunction`** / **`registerTemplateFunctions`**.

Next: [Cart](/frontend-template-engine/cart) and [Checkout](/frontend-template-engine/checkout).