chore: es6 parser (#98)

Signed-off-by: Grant Timmerman <timmerman+devrel@google.com>

lib/formats/json/parser.js

@@ -4,42 +4,35 @@ const {
   isStringOrObjectOrThrow
 } = require("../../utils/fun.js");
 
-function JSONParser(decorator) {
-  this.decorator = decorator;
-}
-
 const invalidPayloadTypeError =
   new Error("invalid payload type, allowed are: string or object");
-
 const nullOrIndefinedPayload =
   new Error("null or undefined payload");
 
-// Function
 const asJSON = (v) => (isString(v) ? JSON.parse(v) : v);
 
-// Level 0 of validation: is that string? is that JSON?
-function validateAndParse(payload) {
-  const json =
-    Array.of(payload)
+class JSONParser {
+  constructor(decorator) {
+    this.decorator = decorator;
+  }
+
+  /**
+   * Parses the payload with an optional decorator
+   * @param {object|string} payload the JSON payload
+   * @return {object} the parsed JSON payload.
+   */
+  parse(payload) {
+    if (this.decorator) {
+      payload = this.decorator.parse(payload);
+    }
+
+    return Array.of(payload)
+
       .filter((p) => isDefinedOrThrow(p, nullOrIndefinedPayload))
       .filter((p) => isStringOrObjectOrThrow(p, invalidPayloadTypeError))
       .map(asJSON)
       .shift();
-
-  return json;
+  }
 }
 
-JSONParser.prototype.parse = function(payload) {
-  let toparse = payload;
-
-  if (this.decorator) {
-    toparse = this.decorator.parse(payload);
-  }
-
-  // is that string? is that JSON?
-  const valid = validateAndParse(toparse);
-
-  return valid;
-};
-
 module.exports = JSONParser;