Fetch

The JavaScript fetch API is available; but we also provide a helper fetchText for issuing requests into a friendly format.

host.fetch

The host.fetch function is a wrapper around the global fetch function which adds builtin proxy support and retry capabilities.

const response = await host.fetch("https://api.example.com", { retries: 3 })

host.fetchText

Use host.fetchText to issue requests and download text from the internet.

const { text, file } = await host.fetchText("https://....")
if (text) $`And also ${text}`

def("FILE", file)

fetchText will also resolve the contents of file in the current workspace if the url is a relative path.

const { file } = await host.fetchText("README.md")
def("README", file)

HTML to markdown or text

fetchText provides various converters to extract the text from the HTML source to a more compact text representation. If you plan to use HTML source in your LLM calls, you will surely run out of context!

// markdown
const md = await host.fetch("https://...", { convert: "markdown" })
// text
const md = await host.fetch("https://...", { convert: "text" })

host.resolveResource

Use host.resolveResource to resolve and download resources from URLs. This function handles various URL schemes and protocols, and can resolve GitHub blob URLs to raw content, among other transformations.

const result = await host.resolveResource("https://github.com/microsoft/genaiscript/blob/main/docs/public/images/favicon.png")
if (result) {
  console.log(`Resolved URI: ${result.uri}`)
  for (const file of result.files) {
    console.log(`File: ${file.filename}`)
    if (file.content) {
      console.log(`Binary content: ${file.content.length} bytes`)
    } else if (file.text) {
      console.log(`Text content: ${file.text.length} characters`)
    }
  }
}

The function returns an object with:

• uri: The resolved URL as a URL object
• files: An array of resolved files with their content

Domain Filtering

Domain filtering restricts which domains can be accessed through GenAIScript’s host APIs (host.fetchText, host.resolveResource). By default, all domains are allowed (*) for convenience, but you can configure specific restrictions.

Scope of Domain Filtering

Domain filtering only applies to GenAIScript’s host APIs (host.fetchText, host.resolveResource). It does NOT affect:

• Global fetch() function
• Third-party libraries making HTTP requests
• Direct network calls from imported packages

This is not an egress proxy - it’s API-level filtering for GenAIScript’s built-in network functions only.

Configuration

You can configure allowed domains in several ways:

Environment Variables:

# Comma-separated list
GENAISCRIPT_ALLOWED_DOMAINS=github.com,*.openai.com,example.org

# YAML array format
GENAISCRIPT_ALLOWED_DOMAINS='["github.com", "*.openai.com", "example.org"]'

Configuration File (genaiscript.config.yml):

allowedDomains:
  - github.com
  - '*.openai.com'
  - example.org

Configuration File (genaiscript.config.json):

{
  "allowedDomains": ["github.com", "*.openai.com", "example.org"]
}

Script-Level Configuration: Individual scripts can specify their own allowed domains, which override the global configuration:

script({
  title: "My Script",
  allowedDomains: [
    "github.com",
    "*.openai.com",
    "example.com"
  ]
})

// This script can only access the domains listed above
const response = await host.fetchText("https://api.openai.com/data")

Script-level configuration takes precedence over global settings, allowing fine-grained control over domain access per script.

Wildcard Patterns

Domain patterns support glob-style wildcards using minimatch:

• github.com - Exact match only
• *.github.com - Matches any subdomain (e.g., api.github.com)
• * - Matches all domains (use with caution)

When a domain is blocked, you’ll see an error message like:

Domain 'example.com' is not allowed. Allowed domains: *.
Configure allowed domains via GENAISCRIPT_ALLOWED_DOMAINS environment variable or allowedDomains in script configuration.

Secrets

If the API you are querying requires an API key, you can use the secrets object to store the key.