2019-4-3

  const seconds = Array.from(document.querySelectorAll('[data-time]'))
    .map((node) => node.dataset.time)
    .map((timeCode) => {
      const [mins, secs] = timeCode.split(':').map(parseFloat);
      return (mins * 60) + secs;
    })
    .reduce((acc, crt) => acc + crt);
  let secondsLeft = seconds;
  const hours = Math.floor(secondsLeft / 3600);
  secondsLeft = secondsLeft % 3600;
  const mins = Math.floor(secondsLeft / 60);
  secondsLeft = secondsLeft % 60;
  console.log(hours, mins, secondsLeft);

console.log(parseFloat('3.24eee')) // 3.24
console.log(Number('3.24eee')) // NaN
// parseFload()会解析到不是数字为止，然后返回是数字的部分
// Number()是严格模式下的parseFloat

flex: 1 1 calc(33.33% - 20px)

// format JSON code
console.log(JSON.stringify({ alpha: 'A', beta: 'B' }, null, '\t'));
// Result:
// '{
//     "alpha": A,
//     "beta": B
// }'