compatibility.md

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📅 Compatibility Dates

• Compatibility Dates Reference

Compatibility Dates

Like the Workers runtime, Miniflare uses compatibility dates to opt-into backwards-incompatible changes from a specific date. If one isn't set, it will default to some time far in the past.

import ConfigTabs from "../components/mdx/config-tabs";

$ miniflare --compat-date 2021-11-12

---
filename: wrangler.toml
---
compatibility_date = "2021-11-12"

const mf = new Miniflare({
  compatibilityDate: "2021-11-12",
});

Compatibility Flags

Miniflare also lets you opt-in/out of specific changes using compatibility flags:

$ miniflare --compat-flag formdata_parser_supports_files --compat-flag durable_object_fetch_allows_relative_url

---
filename: wrangler.toml
---
compatibility_flags = [
  "formdata_parser_supports_files",
  "durable_object_fetch_allows_relative_url"
]

const mf = new Miniflare({
  compatibilityFlags: [
    "formdata_parser_supports_files",
    "durable_object_fetch_allows_relative_url",
  ],
});

Specifically Miniflare supports the following flags:

• streams_enable_constructors/streams_disable_constructors
• transformstream_enable_standard_constructor/transformstream_disable_standard_constructor
• global_navigator/no_global_navigator
• durable_object_fetch_requires_full_url/durable_object_fetch_allows_relative_url
• fetch_refuses_unknown_protocols/fetch_treats_unknown_protocols_as_http
• formdata_parser_supports_files/formdata_parser_converts_files_to_strings
• html_rewriter_treats_esi_include_as_void_tag