tmp_balance_check.js

const fs = require('fs');
const code = fs.readFileSync('src/App.jsx', 'utf8');
let stack = [];
let line = 1, col = 1;
let inSingle = false, inDouble = false, inTemplate = false, inComment = false, inBlock = false;
for (let i = 0; i < code.length; i++) {
  const c = code[i];
  const next = code[i+1];
  if (c === '\n') { line++; col = 1; if (inComment) inComment = false; continue; }
  if (inComment) { col++; continue; }
  if (inBlock) {
    if (c === '*' && next === '/') { inBlock = false; i++; col += 2; continue; }
    col++; continue;
  }
  if (!inSingle && !inDouble && !inTemplate && c === '/' && next === '/') { inComment = true; i++; col += 2; continue; }
  if (!inSingle && !inDouble && !inTemplate && c === '/' && next === '*') { inBlock = true; i++; col += 2; continue; }
  if (!inSingle && !inDouble && !inTemplate && c === '`') { inTemplate = true; col++; continue; }
  if (inTemplate) { if (c === '`' && code[i-1] !== '\\') inTemplate = false; col++; continue; }
  if (!inSingle && !inDouble && !inTemplate && c === '"') { inDouble = true; col++; continue; }
  if (inDouble) { if (c === '"' && code[i-1] !== '\\') inDouble = false; col++; continue; }
  if (!inSingle && !inDouble && !inTemplate && c === "'") { inSingle = true; col++; continue; }
  if (inSingle) { if (c === "'" && code[i-1] !== '\\') inSingle = false; col++; continue; }
  if (c === '(' || c === '{' || c === '[') stack.push({ch: c, line, col});
  if (c === ')' || c === '}' || c === ']') {
    const last = stack.pop();
    if (!last) {
      console.log('unmatched closing', c, 'at', line, col);
      process.exit(1);
    }
    const match = { ')': '(', '}': '{', ']': '[' };
    if (last.ch !== match[c]) {
      console.log('mismatch', last, c, line, col);
      process.exit(1);
    }
  }
  col++;
}
if (stack.length === 0) {
  console.log('stack OK');
} else {
  console.log('stack not empty', stack.length, stack.slice(-10));
}