function

Functions allow you to create short, reusable scripts that can be called from any of your other scripts. They are useful for encapsulating logic you use in multiple places - API calls, data transformations, calculations, and more.

To create a function, select the Add new function script button.

Syntax

{% function "function_handle", param1:value1, param2:value2 as result %}

• "function_handle" — the handle (or ID) of the function script to call.

• param1:value1, param2:value2 — named parameters. Each becomes a variable inside the function.

• as result — captures the function's return value into a variable.

Parameters

Named parameters let you pass values directly into the function scope. Each key:value pair becomes a variable accessible inside the function code.

Values can be variables, string literals, or any Liquid expression:

{% assign user_email = "[email protected]" %}

{% function "send_email", email:user_email, subject:"Welcome!" as email_result %}

Inside the function, email and subject are available as regular variables.

You can pass as many parameters as needed:

{% comment %}Inside webhook orders/paid script{% endcomment %}
{% assign order = payload %}
{% function "create_order_note", order_id:order.id, message:"Note text", priority:"high", notify:true as note_result %}
{% log note_result %}

Return values

Functions return a value using the return tag. The returned value is captured by the as clause.

Function code (handle: add_numbers):

{% comment %}Inside function script{% endcomment %}
{% assign sum = a | plus: b %}
{% return sum %}

Calling the function:

{% function "add_numbers", a:5, b:3 as sum_result %}
{% log "This is result: " | append: sum_result %}

Output: The sum is: 8

The as sum_result clause saves the return value so you can use it later in your script — log it, pass it to another function, or use it in conditions:

{% function "add_numbers", a:5, b:3 as sum_result %}
{% if sum_result > 5 %}
  {% log "Sum is greater than 5" %}
{% endif %}

Without as

The as variable clause is optional. If omitted, the function's return value is written directly to the output:

{% function "add_numbers", a:5, b:3 %}

This also outputs 8, but you cannot reference the result later in your script.

Example: Send metrics to Klaviyo

Function code (handle: send_metric_to_klaviyo):

{% json body %}
{
  "data": {
    "type": "event",
    "attributes": {
      "properties": {
        "membership": {{ property | default: "" | json }}
      },
      "metric": {
        "data": {
          "type": "metric",
          "attributes": {
            "name": {{ metric | default: "" | json }}
          }
        }
      },
      "profile": {
        "data": {
          "type": "profile",
          "attributes": {
            "email": {{ email | default: "" | json }}
          }
        }
      }
    }
  }
}
{% endjson %}

{% json request_options %}
{
  "url": "https://a.klaviyo.com/client/events/?company_id={{KLAVIYO_TOKEN}}",
  "method": "POST",
  "headers": {
    "Content-Type": "application/json",
    "Accept": "application/json",
    "Revision": "2024-05-15"
  },
  "body": {{ body | json }}
}
{% endjson %}
{% http url:request_options.url, method:request_options.method, body:request_options.body, headers:request_options.headers as response %}
{% return response %}

Notice that email, property, and metric are used directly as variables — they are injected into the function scope when the function is called.

Calling the function from another script:

{% assign user_email = "[email protected]" %}
{% assign membership_level = "GOLD" %}

{% function "send_metric_to_klaviyo", email:user_email, property:membership_level, metric:"MEMBERSHIP UPDATE" as fn_result %}

{% log fn_result %}

After execution, fn_result contains the result of the HTTP call made inside send_metric_to_klaviyo.

Example: Reusable GraphQL helper

Function code (handle: get_product_title):

{% capture query %}
  query { product(id: "{{ product_id }}") { title } }
{% endcapture %}
{% graphql query:query as gql_result %}
{% return gql_result.data.product.title %}

Calling the function:

{% function "get_product_title", product_id:"gid://shopify/Product/123456" as title %}
{% log title %}

Example: Calling a function inside a loop

Functions are especially useful inside loops where you need to perform the same operation for each item:

{% for item in order.line_items %}
  {% function "check_inventory", variant_id:item.variant_id, quantity:item.quantity as stock_status %}
  {% if stock_status.available == false %}
    {% log "Out of stock: " | append: item.title %}
  {% endif %}
{% endfor %}

Legacy format: JSON payload

The old format using a single JSON payload variable is still supported. All keys from the payload object are spread into the function scope.

{% json fn_input %}
{
  "email": "[email protected]",
  "property": "GOLD",
  "metric": "MEMBERSHIP UPDATE"
}
{% endjson %}

{% function "send_metric_to_klaviyo", fn_input as fn_result %}

{% log fn_result %}

Note: Named parameters and the JSON payload format cannot be mixed in a single call. Use one or the other.

Limitations

• No nested function calls — you cannot call a function from inside another function.

• Task variables are not available inside functions. Pass any values you need as parameters.

• Global variables are accessible inside functions.