Environments:

• Prettier Version: 1.15.x
• Running Prettier via: Webpack, UglifyJS
• Runtime: Node.js v6, Node.js v8
• Operating System: ALL

Steps to reproduce:

Build your application with Webpack and UglifyJS targeting ES5.

Expected behavior:
The applications should build correctly with ES5 without using any parser to compile external libraries (i.e. Prettier).

Actual behavior:
The build fails due to:

ERROR in vendor.b5330e7b0af9bd05ebf3.chunk.js from UglifyJs
Unexpected token: keyword (const) [./node_modules/prettier/standalone.js:18962,0][vendor.b5330e7b0af9bd05ebf3.chunk.js:45354,0]

The issue was introduced in this commit: 9120689#diff-863f7f2568e0a7b62f866fcadb68d31e as part of this PR #5040 for Prettier 1.15.x.

Basically, this destructuring assignment:

const {
   cjkPattern,
   kPattern,
   punctuationPattern
 } = require("./constants.evaluate");

is not correctly parsed to ES5 when building/releasing the Prettier package. In the distribution package the standalone.js file is like this:

// "const" is not ES5, but ES6 standard
const json$9 = {"cjkPattern":"[...]","kPattern":"[...]","punctuationPattern":"[...]"};

var cjkPattern = json$9.cjkPattern;
var kPattern = json$9.kPattern;
var punctuationPattern$1 = json$9.punctuationPattern;