Format number Vue directive

format-number.js

export default {
  install: Vue => Vue.filter('format-number', (value, { thousand = ' ', decimal = '.', decimals = null, maxDecimals = decimals, minDecimals = decimals, normalize = true, roundToEven = true } = {}) => {
    value = normalize ? normalizeNumber(value) : `${value != null ? value : ''}`;
    let pieces = value.split('.');
    if (!pieces[0].length) {
      return;
    }

    if (minDecimals > 0) {
      pieces[1] = (pieces[1] = pieces[1] || '').padEnd(minDecimals, '0');
    }
    if (maxDecimals != null && maxDecimals >= 0 && (pieces[1] || '').length > maxDecimals) {
      const digit = +pieces[1][maxDecimals];
      pieces[1] = pieces[1].slice(0, maxDecimals);
      let digits = pieces.join('');
      if (digit > 5 || (digit === 5 && (!roundToEven || (digits.slice(-1) & 1)))) {
        digits = digits.replace(/([^-9]?)(9*)$/, (_, digit, nines) => `${++digit}${''.padEnd(nines.length, '0')}`);
        const length = digits.length - maxDecimals;
        pieces = [digits.slice(0, length), digits.slice(length)];
      }
      if (!maxDecimals) {
        pieces.pop();
      }
    }
    pieces[0] = pieces[0].replace(/\d(?=(?:\d{3})+$)/g, `$&${thousand}`);

    return pieces.join(decimal);
  })
};

function normalizeNumber (value, { isDecimal = true, isUnsigned = false, decimalSeparator = '.' } = {}) {
  if (!(value = value != null && `${value}`)) {
    return '';
  }
  const isNegative = /^\s*-/.test(value) && !isUnsigned;
  value = value.replace(isDecimal ? /[^\d,.]/g : /\D/g, '');
  if (isDecimal) {
    const pieces = value.split(/[,.]/);
    const decimal = pieces.pop().replace(/0+$/, '');
    if (pieces.length) {
      value = `${pieces.join('') || (decimal ? '0' : '')}${decimal ? `${decimalSeparator}${decimal}` : ''}`;
    }
  }
  value = value.replace(/^(?:0(?!\b))+/, '');
  if (isNegative) {
    value = value ? `-${value}` : '';
  }
  return value;
}