feat(htmlvalidate): add `getElementsSchema()` to get effective elements schema

fixes #78

src/htmlvalidate.spec.ts

@@ -535,13 +535,27 @@ describe("HtmlValidate", () => {
 		`);
 	});
 
-	it("getConfiurationSchema() should get configuration schema", () => {
+	it("getConfiurationSchema() should get effective configuration schema", () => {
 		expect.assertions(1);
 		const htmlvalidate = new HtmlValidate();
 		const schema = htmlvalidate.getConfigurationSchema();
 		expect(schema).not.toBeUndefined();
 	});
 
+	it("getElementsSchema() should get effective elements schema", () => {
+		expect.assertions(1);
+		const htmlvalidate = new HtmlValidate();
+		const schema = htmlvalidate.getElementsSchema("./path/to/elements.json");
+		expect(schema).not.toBeUndefined();
+	});
+
+	it("getElementsSchema() should not require filename", () => {
+		expect.assertions(1);
+		const htmlvalidate = new HtmlValidate();
+		const schema = htmlvalidate.getElementsSchema();
+		expect(schema).not.toBeUndefined();
+	});
+
 	it("getRuleDocumentation() should delegate call to engine", () => {
 		expect.assertions(1);
 		const htmlvalidate = new HtmlValidate();

src/htmlvalidate.ts

@@ -221,10 +221,27 @@ class HtmlValidate {
 		}, [] as string[]);
 	}
 
+	/**
+	 * Get effective configuration schema.
+	 */
 	public getConfigurationSchema(): SchemaObject {
 		return configurationSchema;
 	}
 
+	/**
+	 * Get effective metadata element schema.
+	 *
+	 * If a filename is given the configured plugins can extend the
+	 * schema. Filename must not be an existing file or a filetype normally
+	 * handled by html-validate but the path will be used when resolving
+	 * configuration. As a rule-of-thumb, set it to the elements json file.
+	 */
+	public getElementsSchema(filename?: string): SchemaObject {
+		const config = this.getConfigFor(filename ?? "inline");
+		const metaTable = config.getMetaTable();
+		return metaTable.getJSONSchema();
+	}
+
 	/**
 	 * Get contextual documentation for the given rule.
 	 *

src/meta/table.ts

 import Ajv, { KeywordDefinition, ValidateFunction } from "ajv";
-import { DataValidateFunction, DataValidationCxt } from "ajv/dist/types";
+import { DataValidateFunction, DataValidationCxt, SchemaObject } from "ajv/dist/types";
 import deepmerge from "deepmerge";
 import jsonMergePatch from "json-merge-patch";
 import { HtmlElement } from "../dom";
@@ -76,9 +76,7 @@ const ajvRegexpKeyword: KeywordDefinition = {
 export class MetaTable {
 	public readonly elements: ElementTable;
 
-	/* jsonMergePatch.apply returns Object */
-	/* eslint-disable-next-line @typescript-eslint/ban-types */
-	private schema: Object;
+	private schema: SchemaObject;
 
 	public constructor() {
 		this.elements = {};
@@ -218,6 +216,10 @@ export class MetaTable {
 		return ajv.compile<MetaDataTable>(this.schema);
 	}
 
+	public getJSONSchema(): SchemaObject {
+		return this.schema;
+	}
+
 	/**
 	 * Finds the global element definition and merges each known element with the
 	 * global, e.g. to assign global attributes.