📅 Compatibility Dates

• Compatibility Dates ReferenceOpen external link

​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.

Using the CLICLI
Using wrangler.tomlwrangler.toml
Using the APIJavaScript API
$ miniflare --compat-date 2021-11-12
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:

Using the CLICLI
Using wrangler.tomlwrangler.toml
Using the APIJavaScript API
$ miniflare --compat-flag formdata_parser_supports_files --compat-flag durable_object_fetch_allows_relative_url
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:

• nodejs_compat (specifically the node:assert, node:async_hooks, node:buffer, node:events, node:util modules)
• transformstream_enable_standard_constructor/transformstream_disable_standard_constructorOpen external link
• streams_enable_constructors/streams_disable_constructorsOpen external link
• export_commonjs_default/export_commonjs_namespaceOpen external link
• r2_list_honor_includeOpen external link
• global_navigator/no_global_navigatorOpen external link
• durable_object_fetch_requires_full_url/durable_object_fetch_allows_relative_urlOpen external link
• fetch_refuses_unknown_protocols/fetch_treats_unknown_protocols_as_httpOpen external link
• formdata_parser_supports_files/formdata_parser_converts_files_to_stringsOpen external link
• html_rewriter_treats_esi_include_as_void_tagOpen external link