import * as prettier from 'prettier'; import { ExpressionStatement, CallExpression, Identifier } from 'babel-types'; const formatted = prettier.format("foo ( );", { semi: false }); const isFormatted = prettier.check("foo ( );", { semi: false }); const result = prettier.formatWithCursor(" 1", { cursorOffset: 2 }); const customFormatted = prettier.format("lodash ( )", { parser(text, { babylon }) { const ast = babylon(text); const statement = ast.program.body[0] as ExpressionStatement; const expression = statement.expression as CallExpression; const identifier = expression.callee as Identifier; identifier.name = "_"; return ast; } });