Add jsdocs for tagValueProcessor

src/fxp.d.ts

@@ -11,6 +11,13 @@ type X2jOptions = {
   trimValues: boolean;
   cdataPropName: false | string;
   commentPropName: false | string;
+    /**
+Control how tag value should be parsed. Called only if tag value is not empty
+
+@returns {undefined|null} `undefined` or `null` to set original value.
+@returns {unknown} 1. Different value or value with different data type to set new value. <br>
+2. Same value to set parsed value if `parseTagValue: true`.
+   */
   tagValueProcessor: (tagName: string, tagValue: string, jPath: string, hasAttributes: boolean, isLeafNode: boolean) => unknown;
   attributeValueProcessor: (attrName: string, attrValue: string, jPath: string) => string;
   numberParseOptions: strnumOptions;