属性值去重，后面覆盖前面

    unique(arr, name) {
      var hash = {}
      return arr.reduce(function(acc, cru) {
        if (!hash[cru[name]]) {
          acc.push(cru)
          hash[cru[name]] = acc.length - 1
        } else {
          acc.splice(hash[cru[name]], 1, cru)
        }
        return acc
      }, [])
    },