拼接数据，中间用某个符号串起来

for (let j = 0; j < produceList[i].gauge_diameters.yarn_json.length; j++) {
　　const yarnLength = produceList[i].gauge_diameters.yarn_json.length - 1;
　　if (yarnLength > j) {
   　　produceList[i].gauze += produceList[i].gauge_diameters.yarn_json[j].yarn.name + "+";
   } else if (yarnLength == j) {
   　　produceList[i].gauze += produceList[i].gauge_diameters.yarn_json[j].yarn.name;
   }
}