const result = require("@babel/core").transformSync(
  `
  export default 'hello';
`,
  {
    plugins: [
      function (babel) {
        const { types: t } = babel;

        return {
          visitor: {
            StringLiteral(path) {
              path.replaceWith(
                t.unaryExpression(
                  "typeof",
                  t.callExpression(
                    t.memberExpression(
                      t.numericLiteral(-1),
                      t.identifier("toString")
                    ),
                    []
                  )
                )
              );
            },
          },
        };
      },
    ],
  }
);

console.log(result.code);

export default typeof -1 .toString(); // evaluated as 'number'

export default typeof (-1).toString(); // evaluated as 'string'