chore: 🤖 [WIP] init (remain ts errors)

lib/index.ts

@@ -0,0 +1,103 @@
+import detectNewline from "detect-newline";
+import yaml from "js-yaml";
+
+interface MetaData {
+  [key: string]: any;
+}
+
+/**
+ * @typedef {Object} ParseResult
+ * @property {string} content Markdown source text without metadata.
+ * @property {Object} metadata Plain object of parsed metadata.
+ */
+interface ParseResult {
+  content: string;
+  metadata: string | MetaData;
+}
+
+/**
+ * @param {string} text Markdown source text to parse.
+ * @returns {ParseResult} ParseResult object.
+ * @throws {TypeError} Markdown source text must be a string.
+ * @throws {YAMLException} YAML parser function error.
+ */
+const metadataParser = (text: string): ParseResult => {
+  let METADATA_START: RegExp;
+  let METADATA_END: string | any[];
+  let METADATA_FILE_END: string | any[];
+  let result: ParseResult = {
+    content: text,
+    metadata: "",
+  };
+
+  const validateMarkdownText = () => {
+    if (typeof text !== "string") {
+      throw new TypeError("Markdown source text must be a string.");
+    }
+  };
+
+  const setMetadataPatterns = () => {
+    const newline = detectNewline.graceful(text);
+    METADATA_START = new RegExp(`^---${newline}`);
+    METADATA_END = `${newline}---${newline}`;
+    METADATA_FILE_END = `${newline}---`;
+  };
+
+  const splitTextWithMetadata = () => {
+    const metadataEndIndex = text.indexOf(METADATA_END as string);
+    if (metadataEndIndex !== -1) {
+      result = {
+        content: text.substring(metadataEndIndex + METADATA_END.length),
+        metadata: text.substring(0, metadataEndIndex),
+      };
+    }
+  };
+
+  const splitTextWithOnlyMetadata = () => {
+    if (!result.metadata && text.endsWith(METADATA_FILE_END as string)) {
+      result = {
+        content: "",
+        metadata: text.substring(0, text.length - METADATA_FILE_END.length),
+      };
+    }
+  };
+
+  const extractContentAndMetadata = () => {
+    if (METADATA_START.test(text)) {
+      splitTextWithMetadata();
+      splitTextWithOnlyMetadata();
+    }
+  };
+
+  const removeStartPatternFromMetadata = () => {
+    result = {
+      ...result,
+      metadata: result.metadata
+        ? result.metadata!.replace(METADATA_START, "").trim()
+        : null,
+    };
+  };
+
+  const parseMetadata = () => {
+    const parseResult = result.metadata
+      ? yaml.load(result.metadata as string)
+      : {};
+    result = {
+      ...result,
+      metadata: parseResult as MetaData,
+    };
+  };
+
+  const parse = () => {
+    validateMarkdownText();
+    setMetadataPatterns();
+    extractContentAndMetadata();
+    removeStartPatternFromMetadata();
+    parseMetadata();
+  };
+
+  parse();
+  return result;
+};
+
+export default metadataParser;

package.json

@@ -7,11 +7,13 @@
   },
   "description": "Parse YAML metadata (front matter) in a markdown document",
   "devDependencies": {
+    "@types/js-yaml": "^4.0.2",
     "ascjs": "^4.0.3",
     "c8": "^7.3.5",
     "mkdirp": "^1.0.4",
     "standard": "^16.0.3",
-    "tap": "^14.11.0"
+    "tap": "^14.11.0",
+    "typescript": "^4.3.5"
   },
   "engines": {
     "node": ">=10.0.0"

tsconfig.json

@@ -0,0 +1,21 @@
+{
+  "compilerOptions": {
+    "target": "es2018",
+    "module": "commonjs",
+    "moduleResolution": "node",
+    "lib": ["es2018"],
+    "esModuleInterop": true,
+    "rootDir": "./lib",
+    "outDir": "./dist",
+    "sourceMap": true,
+    "declaration": true,
+    "declarationMap": true,
+    "strict": true,
+    "experimentalDecorators": true,
+    "emitDecoratorMetadata": true,
+    "baseUrl": ".",
+    "types": ["@types/node"]
+  },
+  "exclude": ["node_modules", "dist", "**/*.spec.ts"],
+  "include": ["lib/**/*"]
+}