Missing let/const Declarations Create Implicit Globals Causing Silent Data Corruption

[rishab11250]

Severity

Critical — Silently corrupts leaderboard data without any error

Location

scripts/sync-leaderboard.js:100, 104, 145, 149, 190, 194

Description

Variables are assigned without declaration keywords. The file lacks "use strict",
so these become properties on the global object:

dailyData = JSON.parse(JSON.stringify(overallData));   // implicit global
previousData = [];                                      // implicit global
weeklyData = JSON.parse(JSON.stringify(overallData));   // implicit global
monthlyData = JSON.parse(JSON.stringify(overallData));  // implicit global

If code paths run in parallel (Promise.all, async), shared global state causes
silent data corruption — wrong scores, swapped rankings, duplicate entries —
without any error being thrown.

Why It Matters

• Silent corruption is worse than a crash — users see incorrect rankings
• The sync script is the backbone of the entire application
• Three parallel blocks (daily/weekly/monthly) share the same implicit globals
• "use strict" would make this an immediate runtime error

Fix

"use strict";
let dailyData = JSON.parse(JSON.stringify(overallData));
let previousData = [];
let weeklyData = JSON.parse(JSON.stringify(overallData));
let monthlyData = JSON.parse(JSON.stringify(overallData));

[rishab11250]

I want to work on this issue

[jagdish-15]

Assigning this issue to @rishab11250 since they opened the issue and expressed interest in working on it first.

@Akshita-2307, unfortunately we won't be able to consider the PR for this issue at the moment, as it was opened without requesting assignment, while another contributor had already expressed interest in working on it beforehand.