使用了条件三元运算符来判断 this.temp.id 是否存在且 mt_qty 是否已被赋值

this.temp.id
mt_qty
mt_qty
mt_qty
event.wo_wip

get_MPS005(event) {
  this.temp = Object.assign({}, this.temp, {
    wo_no: event.wo_no,
    dp_no: event.dp_no,
    od_lot: event.od_lot,
    od_no: event.od_no,
    od_seq: event.od_seq,
    cu_no: event.cu_no,
    item_no: event.bo_no,
    item_lv: event.bo_lv,
    mt_qty: (this.temp.id && this.temp.mt_qty) ? this.temp.mt_qty : event.wo_wip,
    mt_unit: event.bo_unit,
    mt_unit_name: event.bo_unit_name,
    mt_ratio: event.bo_ratio,
    mt_unit1: event.bo_unit1,
    mt_unit_name1: event.bo_unit_name1,
    mt_ratio1: event.bo_ratio1,
    mt_qty1: event.wo_wip * (event.bo_ratio1 / event.bo_ratio)
  });
}