gistfile1.js

filtered_boats: function () {
  let filtered = this.boats;

  // the minimums
  let mins = {
    "minPrice": 'price',
    "minLength": 'length',
    ...
  };
  filtered = Object.keys(mins).forEach(k => if (this.filter.options[k] !== null) filtered = filtered.filter(boat => boat[mins[k]] >= this.filter.options[k]));

  // the maximums
  let maxs = {
    "maxPrice": 'price',
    "maxLength": 'length',
    ...
  };
  filtered = Object.keys(maxs).forEach(k => if (this.filter.options[k] !== null) filtered = filtered.filter(boat => boat[maxs[k]] <= this.filter.options[k]));

  // the multi-value filters
  let fields = ['brand', 'model', 'type', ...];
  filtered = fields.forEach(f => if (this.filter.options[f].length > 0) filtered = filtered.filter(boat => this.filter.options[f].indexOf(boat[f]) != -1));