functions

---

Overview

Functions module for invoking custom backend functions.

This module allows you to invoke the custom backend functions defined in the app.

Authentication Modes

This module is available to use with a client in all authentication modes:

• Anonymous or User authentication (base44.functions): Functions are invoked with the current user’s permissions. Anonymous users invoke functions without authentication, while authenticated users invoke functions with their authentication context.
• Service role authentication (base44.asServiceRole.functions): Functions are invoked with elevated admin-level permissions. The function code receives a request with admin authentication context.

Generated Types

If you’re working in a TypeScript project, you can generate types from your backend functions to get autocomplete on function names when calling invoke(). See the Dynamic Types guide to get started.

Methods

invoke()

invoke(functionName, data?): Promise<any>

Invokes a custom backend function by name.

Sends a POST request to a custom backend function deployed to the app. The function receives the provided data as named parameters and returns the result. If any parameter is a File object, the request will automatically be sent as multipart/form-data. Otherwise, it will be sent as JSON.

For streaming responses, non-POST methods, or raw response access, use fetch() instead.

Parameters

Properties

functionName · string · required

The name of the function to invoke.

data · Record<string, any>

An object containing named parameters for the function.

Returns

Promise<any>

Promise resolving to the function’s response. The data property contains the data returned by the function, if there is any.

Examples

Basic function call

const result = await base44.functions.invoke('calculateTotal', {
  items: ['item1', 'item2'],
});
console.log(result.data.total);

---

fetch()

fetch(path, init?): Promise<Response>

Performs a direct HTTP request to a backend function path and returns the native Response.

Use fetch() when you need low-level control that invoke() doesn’t provide, such as:

• Streaming responses, like SSE, chunked text, or NDJSON
• Custom HTTP methods, like PUT, PATCH, or DELETE
• Raw response access, including status codes, headers, and binary bodies

Parameters

Properties

path · string · required

Function path. Leading slash is optional, so /chat and chat are equivalent. For example, '/streaming_demo' or 'reports/export'.

init · RequestInit

Optional RequestInit options such as method, headers, body, and signal. Auth headers are added automatically.

Returns

Promise<Response>

Promise resolving to a native Response.

Examples

Stream an SSE response

const response = await base44.functions.fetch('/chat', {
  method: 'POST',
  headers: { 'Content-Type': 'application/json' },
  body: JSON.stringify({ prompt: 'Hello!' }),
});

const reader = response.body!.getReader();
const decoder = new TextDecoder();

while (true) {
  const { done, value } = await reader.read();
  if (done) break;
  console.log(decoder.decode(value, { stream: true }));
}

Type Definitions

FunctionName

---

FunctionName = keyof FunctionNameRegistry extends never ? string : keyof FunctionNameRegistry

Union of all function names from the FunctionNameRegistry. Defaults to string when no types have been generated.

Example

Using generated function name types

// With generated types, you get autocomplete on function names
await base44.functions.invoke('calculateTotal', { items: ['item1', 'item2'] });

FunctionNameRegistry

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Registry of function names. The types generate command fills this registry, then FunctionName resolves to a union of the keys.