Bug: parse->stringify->parse get different results

Description

const qs = require('qs');
const assert = require('assert');

const str = '&=]p&Qm[UU3]={Qmm&Qm=]]&Qm[[UF3]mi]=mQvmQm;';
const obj = qs.parse(str);
const str1 = qs.stringify(obj);
const obj1 = qs.parse(str1);
assert.deepEqual(obj, obj1);

Contributor guide

Tech stack

javascript

Domain

backend

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.

half day

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

basic JavaScriptunderstanding of qs library

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

50

Research direction

The bug is reproduced with a specific query string input. Start by examining the `parse` and `stringify` functions in the qs library to understand why the round trip fails. Look at the current comments for any hints or attempted fixes. The issue is from 2019 with some discussion, so ensure the latest version still exhibits the bug.