abstract class are not supported

[ncaq]

yarn run v1.15.2
$ parcel build src/main.ts
🚨  /home/ncaq/Desktop/goodbye-rfc-2822-date-time/src/main.ts: SyntaxError: /home/ncaq/Desktop/goodbye-rfc-2822-date-time/src/main.ts: Unexpected token, expected ";" (130:9)

  128 | import "moment/locale/zh-tw";
  129 | 
> 130 | abstract class Site {
      |          ^
  131 |   // 生成されたらmomentの地域設定してコンソールに起動したログを残す.
  132 |   constructor() {
  133 |     // momentのグローバル地域設定.
    at Parser.raise (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:6322:17)
    at Parser.unexpected (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:7638:16)
    at Parser.semicolon (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:7620:40)
    at Parser.parseExpressionStatement (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:10299:10)
    at Parser.parseStatementContent (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:9897:19)
    at Parser.parseStatement (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:9763:17)
    at Parser.parseBlockOrModuleBlockBody (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:10340:25)
    at Parser.parseBlockBody (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:10327:10)
    at Parser.parseTopLevel (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:9692:10)
    at Parser.parse (/home/ncaq/Desktop/goodbye-rfc-2822-date-time/node_modules/@babel/parser/lib/index.js:11209:17)
error Command failed with exit code 1.
info Visit https://yarnpkg.com/en/docs/cli/run for documentation about this command.