Hi Arman,
Please have a look at our documentation to access these properties. PDFJS Express WebViewer Class: TextHighlightAnnotation
Currently it looks like you are using our obfuscated properties, there are no guarantees that these will be the same between builds.
Here are the properties you are looking for:
console.log(highlightAnnot.Id); // ID
console.log(highlightAnnot.Quads); // QUADS
console.log(highlightAnnot.getContents()); // Highlighted text
console.log(highlightAnnot.getPageNumber()); // Page Number
Cheers,
Dustin