var str = `北京 2河北 3河北-邯郸 301河北-保定 302河北-邢台 303山东 4山东-青岛 401山东-烟台 402`;var arrStr = str.split("\n");var result = [];arrStr.map(i => {  let = item = i.split(" ");  if (i.indexOf("-") == -1) {    result.push({      label: item[0],      value: item[1],      key: item[1],      children: []    })  } else {    let city = item[0].split("-");    let cur = result.find(j => j.label == city[0])    cur.children.push({      label: city[1],      value: item[1],      key: item[1],    })  }})console.log(result)console.log(JSON.stringify(result))