数组类型的json转化为json类型的数组

一直一个数组类型的json

var allCityList =[{
    "name" : "阿坝",
    "spellName" : "aba",
    "id" : 5780,
    "fullname" : "四川/阿坝",
    "sortLetters" : "a"
    }, {
    "name" : "阿克苏",
    "spellName" : "akesudi",
    "id" : 6474,
    "fullname" : "新疆/阿克苏",
    "sortLetters" : "a"
    }, {
    "name" : "阿拉善",
    "spellName" : "alashanmeng",
    "id" : 3862,
    "fullname" : "内蒙古/阿拉善",
    "sortLetters" : "a"
    }, {
    "name" : "阿勒泰",
    "spellName" : "aletaidi",
    "id" : 6542,
    "fullname" : "新疆/阿勒泰",
    "sortLetters" : "a"
    }, {
    "name" : "阿里",
    "spellName" : "alidi",
    "id" : 6134,
    "fullname" : "西藏/阿里",
    "sortLetters" : "a"
    }, {
    "name" : "安康",
    "spellName" : "ankang",
    "id" : 6248,
    "fullname" : "陕西/安康",
    "sortLetters" : "a"
    }, {
    "name" : "安庆",
    "spellName" : "anqing",
    "id" : 4482,
    "fullname" : "安徽/安庆",
    "sortLetters" : "a"
    }, {
    "name" : "鞍山",
    "spellName" : "anshan",
    "id" : 3898,
    "fullname" : "辽宁/鞍山",
    "sortLetters" : "a"
    }, {
    "name" : "安顺",
    "spellName" : "anshun",
    "id" : 5861,
    "fullname" : "贵州/安顺",
    "sortLetters" : "a"
    }, {
    "name" : "安阳",
    "spellName" : "anyang",
    "id" : 4966,
    "fullname" : "河南/安阳",
    "sortLetters" : "a"
    }, {
    "name" : "白城",
    "spellName" : "baicheng",
    "id" : 4041,
    "fullname" : "吉林/白城",
    "sortLetters" : "b"
    }, {
    "name" : "百色",
    "spellName" : "baise",
    "id" : 5527,
    "fullname" : "广西/百色",
    "sortLetters" : "b"
    }, {
    "name" : "白沙",
    "spellName" : "baishalizuz",
    "id" : 5582,
    "fullname" : "海南/白沙",
    "sortLetters" : "b"
    }, {
    "name" : "白山",
    "spellName" : "baishan",
    "id" : 4028,
    "fullname" : "吉林/白山",
    "sortLetters" : "b"
    }, {
    "name" : "白银",
    "spellName" : "baiyin",
    "id" : 6279,
    "fullname" : "甘肃/白银",
    "sortLetters" : "b"
    }, {
    "name" : "蚌埠",
    "spellName" : "bangbu",
    "id" : 4452,
    "fullname" : "安徽/蚌埠",
    "sortLetters" : "b"
    }, {
    "name" : "保定",
    "spellName" : "baoding",
    "id" : 3545,
    "fullname" : "河北/保定",
    "sortLetters" : "b"
    }, {
    "name" : "宝鸡",
    "spellName" : "baoji",
    "id" : 6169,
    "fullname" : "陕西/宝鸡",
    "sortLetters" : "b"
    }, {
    "name" : "保山",
    "spellName" : "baoshan",
    "id" : 5961,
    "fullname" : "云南/保山",
    "sortLetters" : "b"
    }, {
    "name" : "保亭",
    "spellName" : "baotinglizu",
    "id" : 5585,
    "fullname" : "海南/保亭",
    "sortLetters" : "b"
    }, {
    "name" : "包头",
    "spellName" : "baotou",
    "id" : 3770,
    "fullname" : "内蒙古/包头",
    "sortLetters" : "b"
    }, {
    "name" : "巴彦淖尔",
    "spellName" : "bayannaoerm",
    "id" : 3854,
    "fullname" : "内蒙古/巴彦淖尔",
    "sortLetters" : "b"
    }, {
    "name" : "巴音郭楞",
    "spellName" : "bayinguolen",
    "id" : 6501,
    "fullname" : "新疆/巴音郭楞",
    "sortLetters" : "b"
    }, {
    "name" : "巴中",
    "spellName" : "bazhong",
    "id" : 5770,
    "fullname" : "四川/巴中",
    "sortLetters" : "b"
    }, {
    "name" : "北海",
    "spellName" : "beihai",
    "id" : 5501,
    "fullname" : "广西/北海",
    "sortLetters" : "b"
    }, {
    "name" : "北京",
    "spellName" : "beijing",
    "id" : 6550,
    "fullname" : "北京/北京",
    "sortLetters" : "b"
    }, {
    "name" : "本溪",
    "spellName" : "benxi",
    "id" : 3914,
    "fullname" : "辽宁/本溪",
    "sortLetters" : "b"
    }, {
    "name" : "毕节地",
    "spellName" : "bijiedi",
    "id" : 5879,
    "fullname" : "贵州/毕节地",
    "sortLetters" : "b"
    }, {
    "name" : "滨州",
    "spellName" : "binzhou",
    "id" : 4867,
    "fullname" : "山东/滨州",
    "sortLetters" : "b"
    }, {
    "name" : "博尔塔拉",
    "spellName" : "boertala",
    "id" : 6520,
    "fullname" : "新疆/博尔塔拉",
    "sortLetters" : "b"
    }, {
    "name" : "沧州",
    "spellName" : "cangzhou",
    "id" : 3601,
    "fullname" : "河北/沧州",
    "sortLetters" : "c"
    }, {
    "name" : "长春",
    "spellName" : "changchun",
    "id" : 3987,
    "fullname" : "吉林/长春",
    "sortLetters" : "c"
    }, {
    "name" : "常德",
    "spellName" : "changde",
    "id" : 5235,
    "fullname" : "湖南/常德",
    "sortLetters" : "c"
    }, {
    "name" : "昌都",
    "spellName" : "changdudi",
    "id" : 6090,
    "fullname" : "西藏/昌都",
    "sortLetters" : "c"
    }, {
    "name" : "昌吉",
    "spellName" : "changji",
    "id" : 6511,
    "fullname" : "新疆/昌吉",
    "sortLetters" : "c"
    }, {
    "name" : "昌江",
    "spellName" : "changjiangl",
    "id" : 5581,
    "fullname" : "海南/昌江",
    "sortLetters" : "c"
    }, {
    "name" : "长沙",
    "spellName" : "changsha",
    "id" : 5174,
    "fullname" : "湖南/长沙",
    "sortLetters" : "c"
    }, {
    "name" : "长治",
    "spellName" : "changzhi",
    "id" : 3667,
    "fullname" : "山西/长治",
    "sortLetters" : "c"
    }, {
    "name" : "常州",
    "spellName" : "changzhou",
    "id" : 4309,
    "fullname" : "江苏/常州",
    "sortLetters" : "c"
    }, {
    "name" : "巢湖",
    "spellName" : "chaohu",
    "id" : 4526,
    "fullname" : "安徽/巢湖",
    "sortLetters" : "c"
    }, {
    "name" : "朝阳",
    "spellName" : "chaoyang",
    "id" : 3979,
    "fullname" : "辽宁/朝阳",
    "sortLetters" : "c"
    }, {
    "name" : "潮州",
    "spellName" : "chaozhou",
    "id" : 5436,
    "fullname" : "广东/潮州",
    "sortLetters" : "c"
    }, {
    "name" : "承德",
    "spellName" : "chengde",
    "id" : 3589,
    "fullname" : "河北/承德",
    "sortLetters" : "c"
    }, {
    "name" : "成都",
    "spellName" : "chengdu",
    "id" : 5630,
    "fullname" : "四川/成都",
    "sortLetters" : "c"
    }, {
    "name" : "澄迈",
    "spellName" : "chengmai",
    "id" : 5578,
    "fullname" : "海南/澄迈",
    "sortLetters" : "c"
    }, {
    "name" : "郴州",
    "spellName" : "chenzhou",
    "id" : 5257,
    "fullname" : "湖南/郴州",
    "sortLetters" : "c"
    }, {
    "name" : "赤峰",
    "spellName" : "chifeng",
    "id" : 3784,
    "fullname" : "内蒙古/赤峰",
    "sortLetters" : "c"
    }, {
    "name" : "池州",
    "spellName" : "chizhou",
    "id" : 4545,
    "fullname" : "安徽/池州",
    "sortLetters" : "c"
    }, {
    "name" : "重庆",
    "spellName" : "chongqing",
    "id" : 5587,
    "fullname" : "重庆/重庆",
    "sortLetters" : "c"
    }, {
    "name" : "崇左",
    "spellName" : "chongzuo",
    "id" : 5563,
    "fullname" : "广西/崇左",
    "sortLetters" : "c"
    }, {
    "name" : "楚雄",
    "spellName" : "chuxiong",
    "id" : 6031,
    "fullname" : "云南/楚雄",
    "sortLetters" : "c"
    }, {
    "name" : "滁州",
    "spellName" : "chuzhou",
    "id" : 4502,
    "fullname" : "安徽/滁州",
    "sortLetters" : "c"
    }, {
    "name" : "大理",
    "spellName" : "dali",
    "id" : 6042,
    "fullname" : "云南/大理",
    "sortLetters" : "d"
    }, {
    "name" : "大连",
    "spellName" : "dalian",
    "id" : 3887,
    "fullname" : "辽宁/大连",
    "sortLetters" : "d"
    }, {
    "name" : "丹东",
    "spellName" : "dandong",
    "id" : 3921,
    "fullname" : "辽宁/丹东",
    "sortLetters" : "d"
    }, {
    "name" : "大庆",
    "spellName" : "daqing",
    "id" : 4120,
    "fullname" : "黑龙江/大庆",
    "sortLetters" : "d"
    }, {
    "name" : "大同",
    "spellName" : "datong",
    "id" : 3651,
    "fullname" : "山西/大同",
    "sortLetters" : "d"
    }, {
    "name" : "大兴安岭",
    "spellName" : "daxinganlin",
    "id" : 4194,
    "fullname" : "黑龙江/大兴安岭",
    "sortLetters" : "d"
    }, {
    "name" : "达州",
    "spellName" : "dazhou",
    "id" : 5746,
    "fullname" : "四川/达州",
    "sortLetters" : "d"
    }, {
    "name" : "德宏",
    "spellName" : "dehong",
    "id" : 6055,
    "fullname" : "云南/德宏",
    "sortLetters" : "d"
    }, {
    "name" : "德阳",
    "spellName" : "deyang",
    "id" : 5671,
    "fullname" : "四川/德阳",
    "sortLetters" : "d"
    }, {
    "name" : "德州",
    "spellName" : "dezhou",
    "id" : 4846,
    "fullname" : "山东/德州",
    "sortLetters" : "d"
    }, {
    "name" : "定安",
    "spellName" : "dingan",
    "id" : 5579,
    "fullname" : "海南/定安",
    "sortLetters" : "d"
    }, {
    "name" : "定西",
    "spellName" : "dingxidi",
    "id" : 6331,
    "fullname" : "甘肃/定西",
    "sortLetters" : "d"
    }, {
    "name" : "迪庆",
    "spellName" : "diqing",
    "id" : 6066,
    "fullname" : "云南/迪庆",
    "sortLetters" : "d"
    }, {
    "name" : "东莞",
    "spellName" : "dongwan",
    "id" : 5380,
    "fullname" : "广东/东莞",
    "sortLetters" : "d"
    }, {
    "name" : "东营",
    "spellName" : "dongying",
    "id" : 4781,
    "fullname" : "山东/东营",
    "sortLetters" : "d"
    }, {
    "name" : "鄂尔多斯",
    "spellName" : "eerduosi",
    "id" : 3806,
    "fullname" : "内蒙古/鄂尔多斯",
    "sortLetters" : "e"
    }, {
    "name" : "恩施",
    "spellName" : "enshi",
    "id" : 5162,
    "fullname" : "湖北/恩施",
    "sortLetters" : "e"
    }, {
    "name" : "鄂州",
    "spellName" : "ezhou",
    "id" : 5129,
    "fullname" : "湖北/鄂州",
    "sortLetters" : "e"
    }, {
    "name" : "防城港",
    "spellName" : "fangchengga",
    "id" : 5506,
    "fullname" : "广西/防城港",
    "sortLetters" : "f"
    }, {
    "name" : "佛山",
    "spellName" : "foshan",
    "id" : 5390,
    "fullname" : "广东/佛山",
    "sortLetters" : "f"
    }, {
    "name" : "抚顺",
    "spellName" : "fushun",
    "id" : 3906,
    "fullname" : "辽宁/抚顺",
    "sortLetters" : "f"
    }, {
    "name" : "阜新",
    "spellName" : "fuxin",
    "id" : 3955,
    "fullname" : "辽宁/阜新",
    "sortLetters" : "f"
    }, {
    "name" : "阜阳",
    "spellName" : "fuyang",
    "id" : 4511,
    "fullname" : "安徽/阜阳",
    "sortLetters" : "f"
    }, {
    "name" : "抚州",
    "spellName" : "fuzhou",
    "id" : 4718,
    "fullname" : "江西/抚州",
    "sortLetters" : "f"
    }, {
    "name" : "福州",
    "spellName" : "fuzhou",
    "id" : 4558,
    "fullname" : "福建/福州",
    "sortLetters" : "f"
    }, {
    "name" : "甘南",
    "spellName" : "gannan",
    "id" : 6349,
    "fullname" : "甘肃/甘南",
    "sortLetters" : "g"
    }, {
    "name" : "赣州",
    "spellName" : "ganzhou",
    "id" : 4677,
    "fullname" : "江西/赣州",
    "sortLetters" : "g"
    }, {
    "name" : "甘孜",
    "spellName" : "ganzi",
    "id" : 5794,
    "fullname" : "四川/甘孜",
    "sortLetters" : "g"
    }, {
    "name" : "广安",
    "spellName" : "guangan",
    "id" : 5740,
    "fullname" : "四川/广安",
    "sortLetters" : "g"
    }, {
    "name" : "广元",
    "spellName" : "guangyuan",
    "id" : 5688,
    "fullname" : "四川/广元",
    "sortLetters" : "g"
    }, {
    "name" : "广州",
    "spellName" : "guangzhou",
    "id" : 5308,
    "fullname" : "广东/广州",
    "sortLetters" : "g"
    }, {
    "name" : "贵港",
    "spellName" : "guigang",
    "id" : 5516,
    "fullname" : "广西/贵港",
    "sortLetters" : "g"
    }, {
    "name" : "桂林",
    "spellName" : "guilin",
    "id" : 5475,
    "fullname" : "广西/桂林",
    "sortLetters" : "g"
    }, {
    "name" : "贵阳",
    "spellName" : "guiyang",
    "id" : 5831,
    "fullname" : "贵州/贵阳",
    "sortLetters" : "g"
    }, {
    "name" : "果洛",
    "spellName" : "guoluo",
    "id" : 6398,
    "fullname" : "青海/果洛",
    "sortLetters" : "g"
    }, {
    "name" : "固原",
    "spellName" : "guyuan",
    "id" : 6436,
    "fullname" : "宁夏/固原",
    "sortLetters" : "g"
    }, {
    "name" : "哈尔滨",
    "spellName" : "haerbin",
    "id" : 4056,
    "fullname" : "黑龙江/哈尔滨",
    "sortLetters" : "h"
    }, {
    "name" : "海北",
    "spellName" : "haibei",
    "id" : 6382,
    "fullname" : "青海/海北",
    "sortLetters" : "h"
    }, {
    "name" : "海东",
    "spellName" : "haidongdi",
    "id" : 6375,
    "fullname" : "青海/海东",
    "sortLetters" : "h"
    }, {
    "name" : "海口",
    "spellName" : "haikou",
    "id" : 5570,
    "fullname" : "海南/海口",
    "sortLetters" : "h"
    }, {
    "name" : "海南",
    "spellName" : "hainan",
    "id" : 6392,
    "fullname" : "青海/海南",
    "sortLetters" : "h"
    }, {
    "name" : "海西",
    "spellName" : "haixi",
    "id" : 6412,
    "fullname" : "青海/海西",
    "sortLetters" : "h"
    }, {
    "name" : "哈密",
    "spellName" : "hamidi",
    "id" : 6461,
    "fullname" : "新疆/哈密",
    "sortLetters" : "h"
    }, {
    "name" : "邯郸",
    "spellName" : "handan",
    "id" : 3505,
    "fullname" : "河北/邯郸",
    "sortLetters" : "h"
    }, {
    "name" : "杭州",
    "spellName" : "hangzhou",
    "id" : 4337,
    "fullname" : "浙江/杭州",
    "sortLetters" : "h"
    }, {
    "name" : "汉中",
    "spellName" : "hanzhong",
    "id" : 6223,
    "fullname" : "陕西/汉中",
    "sortLetters" : "h"
    }, {
    "name" : "亳州",
    "spellName" : "haozhou",
    "id" : 4540,
    "fullname" : "安徽/亳州",
    "sortLetters" : "h"
    }, {
    "name" : "漯河",
    "spellName" : "he",
    "id" : 4990,
    "fullname" : "河南/漯河",
    "sortLetters" : "h"
    }, {
    "name" : "鹤壁",
    "spellName" : "hebi",
    "id" : 4947,
    "fullname" : "河南/鹤壁",
    "sortLetters" : "h"
    }, {
    "name" : "河池",
    "spellName" : "hechi",
    "id" : 5544,
    "fullname" : "广西/河池",
    "sortLetters" : "h"
    }, {
    "name" : "合肥",
    "spellName" : "hefei",
    "id" : 4436,
    "fullname" : "安徽/合肥",
    "sortLetters" : "h"
    }, {
    "name" : "鹤岗",
    "spellName" : "hegang",
    "id" : 4092,
    "fullname" : "黑龙江/鹤岗",
    "sortLetters" : "h"
    }, {
    "name" : "黑河",
    "spellName" : "heihe",
    "id" : 4176,
    "fullname" : "黑龙江/黑河",
    "sortLetters" : "h"
    }, {
    "name" : "衡水",
    "spellName" : "hengshui",
    "id" : 3629,
    "fullname" : "河北/衡水",
    "sortLetters" : "h"
    }, {
    "name" : "衡阳",
    "spellName" : "hengyang",
    "id" : 5200,
    "fullname" : "湖南/衡阳",
    "sortLetters" : "h"
    }, {
    "name" : "和田",
    "spellName" : "hetiandi",
    "id" : 6465,
    "fullname" : "新疆/和田",
    "sortLetters" : "h"
    }, {
    "name" : "河源",
    "spellName" : "heyuan",
    "id" : 5353,
    "fullname" : "广东/河源",
    "sortLetters" : "h"
    }, {
    "name" : "菏泽",
    "spellName" : "heze",
    "id" : 4875,
    "fullname" : "山东/菏泽",
    "sortLetters" : "h"
    }, {
    "name" : "贺州",
    "spellName" : "hezhou",
    "id" : 5539,
    "fullname" : "广西/贺州",
    "sortLetters" : "h"
    }, {
    "name" : "红河",
    "spellName" : "honghe",
    "id" : 6013,
    "fullname" : "云南/红河",
    "sortLetters" : "h"
    }, {
    "name" : "淮安",
    "spellName" : "huaian",
    "id" : 4253,
    "fullname" : "江苏/淮安",
    "sortLetters" : "h"
    }, {
    "name" : "淮北",
    "spellName" : "huaibei",
    "id" : 4472,
    "fullname" : "安徽/淮北",
    "sortLetters" : "h"
    }, {
    "name" : "怀化",
    "spellName" : "huaihua",
    "id" : 5281,
    "fullname" : "湖南/怀化",
    "sortLetters" : "h"
    }, {
    "name" : "淮南",
    "spellName" : "huainan",
    "id" : 4460,
    "fullname" : "安徽/淮南",
    "sortLetters" : "h"
    }, {
    "name" : "黄冈",
    "spellName" : "huanggang",
    "id" : 5141,
    "fullname" : "湖北/黄冈",
    "sortLetters" : "h"
    }, {
    "name" : "黄南",
    "spellName" : "huangnan",
    "id" : 6387,
    "fullname" : "青海/黄南",
    "sortLetters" : "h"
    }, {
    "name" : "黄山",
    "spellName" : "huangshan",
    "id" : 4494,
    "fullname" : "安徽/黄山",
    "sortLetters" : "h"
    }, {
    "name" : "黄石",
    "spellName" : "huangshi",
    "id" : 5074,
    "fullname" : "湖北/黄石",
    "sortLetters" : "h"
    }, {
    "name" : "呼和浩特",
    "spellName" : "huhehaote",
    "id" : 3760,
    "fullname" : "内蒙古/呼和浩特",
    "sortLetters" : "h"
    }, {
    "name" : "惠州",
    "spellName" : "huizhou",
    "id" : 5369,
    "fullname" : "广东/惠州",
    "sortLetters" : "h"
    }, {
    "name" : "葫芦岛",
    "spellName" : "huludao",
    "id" : 3936,
    "fullname" : "辽宁/葫芦岛",
    "sortLetters" : "h"
    }, {
    "name" : "呼伦贝尔",
    "spellName" : "hulunbeier",
    "id" : 3815,
    "fullname" : "内蒙古/呼伦贝尔",
    "sortLetters" : "h"
    }, {
    "name" : "湖州",
    "spellName" : "huzhou",
    "id" : 4383,
    "fullname" : "浙江/湖州",
    "sortLetters" : "h"
    }, {
    "name" : "佳木斯",
    "spellName" : "jiamusi",
    "id" : 4159,
    "fullname" : "黑龙江/佳木斯",
    "sortLetters" : "j"
    }, {
    "name" : "吉安",
    "spellName" : "jian",
    "id" : 4695,
    "fullname" : "江西/吉安",
    "sortLetters" : "j"
    }, {
    "name" : "江门",
    "spellName" : "jiangmen",
    "id" : 5382,
    "fullname" : "广东/江门",
    "sortLetters" : "j"
    }, {
    "name" : "焦作",
    "spellName" : "jiaozuo",
    "id" : 4936,
    "fullname" : "河南/焦作",
    "sortLetters" : "j"
    }, {
    "name" : "嘉兴",
    "spellName" : "jiaxing",
    "id" : 4375,
    "fullname" : "浙江/嘉兴",
    "sortLetters" : "j"
    }, {
    "name" : "嘉峪关",
    "spellName" : "jiayuguan",
    "id" : 6293,
    "fullname" : "甘肃/嘉峪关",
    "sortLetters" : "j"
    }, {
    "name" : "嘉峪关",
    "spellName" : "Jiayuguan",
    "id" : 6556,
    "fullname" : "甘肃/嘉峪关/嘉峪关",
    "sortLetters" : "J"
    }, {
    "name" : "揭阳",
    "spellName" : "jieyang",
    "id" : 5440,
    "fullname" : "广东/揭阳",
    "sortLetters" : "j"
    }, {
    "name" : "吉林",
    "spellName" : "jilin",
    "id" : 3998,
    "fullname" : "吉林/吉林",
    "sortLetters" : "j"
    }, {
    "name" : "济南",
    "spellName" : "jinan",
    "id" : 4741,
    "fullname" : "山东/济南",
    "sortLetters" : "j"
    }, {
    "name" : "金昌",
    "spellName" : "jinchang",
    "id" : 6276,
    "fullname" : "甘肃/金昌",
    "sortLetters" : "j"
    }, {
    "name" : "晋城",
    "spellName" : "jincheng",
    "id" : 3680,
    "fullname" : "山西/晋城",
    "sortLetters" : "j"
    }, {
    "name" : "景德镇",
    "spellName" : "jingdezhen",
    "id" : 4651,
    "fullname" : "江西/景德镇",
    "sortLetters" : "j"
    }, {
    "name" : "荆门",
    "spellName" : "jingmen",
    "id" : 5123,
    "fullname" : "湖北/荆门",
    "sortLetters" : "j"
    }, {
    "name" : "荆州",
    "spellName" : "jingzhou",
    "id" : 5100,
    "fullname" : "湖北/荆州",
    "sortLetters" : "j"
    }, {
    "name" : "金华",
    "spellName" : "jinhua",
    "id" : 4394,
    "fullname" : "浙江/金华",
    "sortLetters" : "j"
    }, {
    "name" : "济宁",
    "spellName" : "jining",
    "id" : 4818,
    "fullname" : "山东/济宁",
    "sortLetters" : "j"
    }, {
    "name" : "晋中",
    "spellName" : "jinzhong",
    "id" : 3692,
    "fullname" : "山西/晋中",
    "sortLetters" : "j"
    }, {
    "name" : "锦州",
    "spellName" : "jinzhou",
    "id" : 3928,
    "fullname" : "辽宁/锦州",
    "sortLetters" : "j"
    }, {
    "name" : "九江",
    "spellName" : "jiujiang",
    "id" : 4660,
    "fullname" : "江西/九江",
    "sortLetters" : "j"
    }, {
    "name" : "酒泉",
    "spellName" : "jiuquan",
    "id" : 6314,
    "fullname" : "甘肃/酒泉",
    "sortLetters" : "j"
    }, {
    "name" : "鸡西",
    "spellName" : "jixi",
    "id" : 4110,
    "fullname" : "黑龙江/鸡西",
    "sortLetters" : "j"
    }, {
    "name" : "开封",
    "spellName" : "kaifeng",
    "id" : 4898,
    "fullname" : "河南/开封",
    "sortLetters" : "k"
    }, {
    "name" : "喀什",
    "spellName" : "kashidi",
    "id" : 6484,
    "fullname" : "新疆/喀什",
    "sortLetters" : "k"
    }, {
    "name" : "克拉玛依",
    "spellName" : "kelamayi",
    "id" : 6451,
    "fullname" : "新疆/克拉玛依",
    "sortLetters" : "k"
    }, {
    "name" : "克孜勒苏",
    "spellName" : "kezilesu",
    "id" : 6497,
    "fullname" : "新疆/克孜勒苏",
    "sortLetters" : "k"
    }, {
    "name" : "昆明",
    "spellName" : "kunming",
    "id" : 5927,
    "fullname" : "云南/昆明",
    "sortLetters" : "k"
    }, {
    "name" : "来宾",
    "spellName" : "laibin",
    "id" : 5556,
    "fullname" : "广西/来宾",
    "sortLetters" : "l"
    }, {
    "name" : "莱芜",
    "spellName" : "laiwu",
    "id" : 4830,
    "fullname" : "山东/莱芜",
    "sortLetters" : "l"
    }, {
    "name" : "廊坊",
    "spellName" : "langfang",
    "id" : 3618,
    "fullname" : "河北/廊坊",
    "sortLetters" : "l"
    }, {
    "name" : "兰州",
    "spellName" : "lanzhou",
    "id" : 6267,
    "fullname" : "甘肃/兰州",
    "sortLetters" : "l"
    }, {
    "name" : "拉萨",
    "spellName" : "lasa",
    "id" : 6070,
    "fullname" : "西藏/拉萨",
    "sortLetters" : "l"
    }, {
    "name" : "乐东",
    "spellName" : "ledonglizuz",
    "id" : 5586,
    "fullname" : "海南/乐东",
    "sortLetters" : "l"
    }, {
    "name" : "乐山",
    "spellName" : "leshan",
    "id" : 5707,
    "fullname" : "四川/乐山",
    "sortLetters" : "l"
    }, {
    "name" : "凉山",
    "spellName" : "liangshan",
    "id" : 5813,
    "fullname" : "四川/凉山",
    "sortLetters" : "l"
    }, {
    "name" : "连云港",
    "spellName" : "lianyungang",
    "id" : 4245,
    "fullname" : "江苏/连云港",
    "sortLetters" : "l"
    }, {
    "name" : "聊城",
    "spellName" : "liaocheng",
    "id" : 4858,
    "fullname" : "山东/聊城",
    "sortLetters" : "l"
    }, {
    "name" : "辽阳",
    "spellName" : "liaoyang",
    "id" : 3963,
    "fullname" : "辽宁/辽阳",
    "sortLetters" : "l"
    }, {
    "name" : "辽源",
    "spellName" : "liaoyuan",
    "id" : 4015,
    "fullname" : "吉林/辽源",
    "sortLetters" : "l"
    }, {
    "name" : "丽江",
    "spellName" : "lijiang",
    "id" : 5999,
    "fullname" : "云南/丽江",
    "sortLetters" : "l"
    }, {
    "name" : "临沧",
    "spellName" : "lincangdi",
    "id" : 5990,
    "fullname" : "云南/临沧",
    "sortLetters" : "l"
    }, {
    "name" : "临汾",
    "spellName" : "linfen",
    "id" : 3730,
    "fullname" : "山西/临汾",
    "sortLetters" : "l"
    }, {
    "name" : "陵水",
    "spellName" : "lingshuiliz",
    "id" : 5584,
    "fullname" : "海南/陵水",
    "sortLetters" : "l"
    }, {
    "name" : "临夏",
    "spellName" : "linxia",
    "id" : 6358,
    "fullname" : "甘肃/临夏",
    "sortLetters" : "l"
    }, {
    "name" : "临沂",
    "spellName" : "linyi",
    "id" : 4833,
    "fullname" : "山东/临沂",
    "sortLetters" : "l"
    }, {
    "name" : "林芝",
    "spellName" : "linzhidi",
    "id" : 6142,
    "fullname" : "西藏/林芝",
    "sortLetters" : "l"
    }, {
    "name" : "丽水",
    "spellName" : "lishui",
    "id" : 4426,
    "fullname" : "浙江/丽水",
    "sortLetters" : "l"
    }, {
    "name" : "六安",
    "spellName" : "liuan",
    "id" : 4532,
    "fullname" : "安徽/六安",
    "sortLetters" : "l"
    }, {
    "name" : "六盘水",
    "spellName" : "liupanshui",
    "id" : 5842,
    "fullname" : "贵州/六盘水",
    "sortLetters" : "l"
    }, {
    "name" : "柳州",
    "spellName" : "liuzhou",
    "id" : 5464,
    "fullname" : "广西/柳州",
    "sortLetters" : "l"
}]

for(var i=0;i<allCityList.length;i++){
  if(arr.indexOf(allCityList[i].sortLetters)==-1){
    arr.push(allCityList[i].sortLetters)
  } 
}
var json={};
for(var j=0;j<arr.length;j++){
  let key=arr[j];
  jsont[key]=[];
  for(var xx=0;xx<allCityList.length;xx++){
    if(key==allCityList[xx].sortLetters){
      json[key].push(allCityList[xx])
    }
  }
}   
console.log(json)

输出结果为