Reading a BIG stats.json file

readStatsJson.js

let JSONStream = require('jsonstream');
let fs = require('fs');
let es = require('event-stream');

function readStatsJson(path) {
    return new Promise((resolve, reject) => {
        let parsedObject = {};

        let stream = fs
            .createReadStream(path, { encoding: 'utf8' })
            .pipe(JSONStream.parse('$*'))
            .pipe(
                es.mapSync(data => {
                    parsedObject[data.key] = data.value;
                })
            );

        stream.on('close', () => {
            resolve(parsedObject);
        });

        stream.on('error', reject);
    });
}

When webpack's stats get really big, it isn't possible to read in the file as a single string. (You'll get RangeError: Invalid string length.) This is a solution to read and parse the file via a stream. Given how big the stats are, you'll probably need to give node more memory (e.g. --max-old-space-size=4096).

Note that you can't write an overlarge stats object with JSONStream, because internally it still tries to use the native JSON.stringify on the object. For that, the only thing I found that works is BFJ.