row.meta.cursor in step always same value when parsing in worker mode

Description

Papa.parse(file, {
  header: true,
  worker: true, // << worker is true
  step: (row, parser) => {
    console.log(row.meta.cursor, file.size);
    // => logs "677403 677403" 8973 times
  },
});

Papa.parse(file, {
  header: true,
  worker: false, // << worker is false
  step: (row, parser) => {
    console.log(row.meta.cursor, file.size);
    // => logs increasisng number upto filesize as expected
  },
});

Contributor guide

Tech stack

javascript

Domain

data

Issue type

bug

DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.

3

Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.

1-3 hours

Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.

stale

ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.

clear

Prerequisites

JavaScriptWeb WorkersPapaParse API

Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.

60

Research direction

Investigate the worker mode implementation in PapaParse, focusing on how the cursor is communicated between the worker and main thread. Look at the source code for the worker script (likely in the src directory) and see how step callbacks are handled. Check if there is a known fix or discussion in the comments of issue #465.