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Version: 3.13.0

allowDynamicBackends

The allowDynamicBackends() function is used to control whether or not Dynamic Backends should be allowed within this Fastly Compute Service.

By default, Dynamic Backends are disabled within a JavaScript application as it can be a potential avenue for third-party JavaScript code to send requests, potentially including sensitive/secret data, off to destinations that the JavaScript project was not intending, which could be a security issue.

Note: This feature is in disabled by default for Fastly Services. Please contact Fastly Support to request the feature be enabled on the Fastly Services which require Dynamic Backends.

Syntax​

allowDynamicBackends(enabled)

Parameters​

  • enabled : boolean
    • Whether or not to allow Dynamic Backends

Return value​

undefined.

Examples​

In this example an implicit Dynamic Backend is created when making the fetch request to https://www.fastly.com/ and the response is then returned to the client.

/// <reference types="@fastly/js-compute" />
import { allowDynamicBackends } from "fastly:experimental";
allowDynamicBackends(true);
async function app() {
  // For any request, return the fastly homepage -- without defining a backend!
  return fetch('https://www.fastly.com/');
}
addEventListener("fetch", event => event.respondWith(app(event)));