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'use strict';
const {
ArrayPrototypeFilter,
ArrayPrototypeIncludes,
ObjectKeys,
ObjectValues,
ObjectPrototypeHasOwnProperty,
} = primordials;
const { validateString } = require('internal/validators');
const {
ERR_IMPORT_ASSERTION_TYPE_FAILED,
ERR_IMPORT_ASSERTION_TYPE_MISSING,
ERR_IMPORT_ASSERTION_TYPE_UNSUPPORTED,
} = require('internal/errors').codes;
// The HTML spec has an implied default type of `'javascript'`.
const kImplicitAssertType = 'javascript';
let alreadyWarned = false;
/**
* Define a map of module formats to import assertion types (the value of
* `type` in `assert { type: 'json' }`).
* @type {Map<string, string>}
*/
const formatTypeMap = {
'__proto__': null,
'builtin': kImplicitAssertType,
'commonjs': kImplicitAssertType,
'json': 'json',
'module': kImplicitAssertType,
'wasm': kImplicitAssertType, // It's unclear whether the HTML spec will require an assertion type or not for Wasm; see https://github.com/WebAssembly/esm-integration/issues/42
};
/**
* The HTML spec disallows the default type to be explicitly specified
* (for now); so `import './file.js'` is okay but
* `import './file.js' assert { type: 'javascript' }` throws.
* @type {Array<string, string>}
*/
const supportedAssertionTypes = ArrayPrototypeFilter(
ObjectValues(formatTypeMap),
(type) => type !== kImplicitAssertType);
/**
* Test a module's import assertions.
* @param {string} url The URL of the imported module, for error reporting.
* @param {string} format One of Node's supported translators
* @param {Record<string, string>} importAssertions Validations for the
* module import.
* @returns {true}
* @throws {TypeError} If the format and assertion type are incompatible.
*/
function validateAssertions(url, format,
importAssertions = { __proto__: null }) {
const validType = formatTypeMap[format];
if (!alreadyWarned && ObjectKeys(importAssertions).length !== 0) {
alreadyWarned = true;
process.emitWarning(
'Import assertions are not a stable feature of the JavaScript language. ' +
'Avoid relying on their current behavior and syntax as those might change ' +
'in a future version of Node.js.',
'ExperimentalWarning',
);
}
switch (validType) {
case undefined:
// Ignore assertions for module formats we don't recognize, to allow new
// formats in the future.
return true;
case kImplicitAssertType:
// This format doesn't allow an import assertion type, so the property
// must not be set on the import assertions object.
if (!ObjectPrototypeHasOwnProperty(importAssertions, 'type')) {
return true;
}
return handleInvalidType(url, importAssertions.type);
case importAssertions.type:
// The asserted type is the valid type for this format.
return true;
default:
// There is an expected type for this format, but the value of
// `importAssertions.type` might not have been it.
if (!ObjectPrototypeHasOwnProperty(importAssertions, 'type')) {
// `type` wasn't specified at all.
throw new ERR_IMPORT_ASSERTION_TYPE_MISSING(url, validType);
}
return handleInvalidType(url, importAssertions.type);
}
}
/**
* Throw the correct error depending on what's wrong with the type assertion.
* @param {string} url The resolved URL for the module to be imported
* @param {string} type The value of the import assertion `type` property
*/
function handleInvalidType(url, type) {
// `type` might have not been a string.
validateString(type, 'type');
// `type` might not have been one of the types we understand.
if (!ArrayPrototypeIncludes(supportedAssertionTypes, type)) {
throw new ERR_IMPORT_ASSERTION_TYPE_UNSUPPORTED(type);
}
// `type` was the wrong value for this format.
throw new ERR_IMPORT_ASSERTION_TYPE_FAILED(url, type);
}
module.exports = {
kImplicitAssertType,
validateAssertions,
};
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