@coffeeandfun/maths-captcha/src/stats.js

Maths-Captcha is a simple Node.js module that generates random math questions to verify human interaction. It creates math problems like addition, subtraction, multiplication, division, powers, percentages, sequences, and algebra, and checks if the user's

const OPERATION_DIFFICULTY = {
  '+': 1,
  '-': 2,
  '*': 3,
  '/': 4,
  '%': 4,
  '^': 5,
  '√': 5,
  expr: 6,
  pct: 4,
  solve: 7,
  seq: 6,
};

export function getQuestionStats(question) {
  const [num1, num2] = question.operands;
  const result = question.numericAnswer;

  return {
    operands: { num1, num2 },
    result,
    operation: question.operation,
    difficulty: calculateDifficulty(question),
    hasDecimals:
      question.operation === '/' ||
      (typeof result === 'number' && !Number.isInteger(result)),
  };
}

export function calculateDifficulty(question) {
  const operands = question.operands ?? [];
  const { operation } = question;

  let score = 1;
  score += OPERATION_DIFFICULTY[operation] ?? 1;

  const numericOperands = operands.filter((value) => typeof value === 'number');
  const maxOperand = numericOperands.length
    ? Math.max(...numericOperands.map(Math.abs))
    : 0;
  if (maxOperand > 50) score += 2;
  else if (maxOperand > 20) score += 1;

  const answerHasDecimal =
    typeof question.answer === 'string' && question.answer.includes('.');
  if (operation === '/' && answerHasDecimal) score += 2;

  if (typeof question.numericAnswer === 'number' && question.numericAnswer > 100) {
    score += 1;
  }

  return Math.min(score, 10);
}