support esm modules

report-bundle-size.js

@@ -7,13 +7,13 @@
 
 // edited to work with the appdir by @raphaelbadia
 
-const gzSize = require("gzip-size")
-const mkdirp = require("mkdirp")
-const fs = require("fs")
-const path = require("path")
+import gzSize from "gzip-size"
+import { mkdirp } from "mkdirp"
+import fs from "fs"
+import path from "path"
 
 // Pull options from `package.json`
-const options = getOptions()
+const options = await getOptions()
 const BUILD_OUTPUT_DIRECTORY = getBuildOutputDirectory(options)
 
 // first we check to make sure that the build output directory exists
@@ -28,8 +28,12 @@ try {
 }
 
 // if so, we can import the build manifest
-const buildMeta = require(path.join(nextMetaRoot, "build-manifest.json"))
-const appDirMeta = require(path.join(nextMetaRoot, "app-build-manifest.json"))
+const { default: buildMeta } = await import(path.join(nextMetaRoot, "build-manifest.json"), {
+  assert: { type: "json" },
+})
+const { default: appDirMeta } = await import(path.join(nextMetaRoot, "app-build-manifest.json"), {
+  assert: { type: "json" },
+})
 
 // this memory cache ensures we dont read any script file more than once
 // bundles are often shared between pages
@@ -116,8 +120,8 @@ function getScriptSize(scriptPath) {
 /**
  * Reads options from `package.json`
  */
-function getOptions(pathPrefix = process.cwd()) {
-  const pkg = require(path.join(pathPrefix, "package.json"))
+async function getOptions(pathPrefix = process.cwd()) {
+  const pkg = await import(path.join(pathPrefix, "package.json"), { assert: { type: "json" } })
 
   return { ...pkg.nextBundleAnalysis, name: pkg.name }
 }