循环遍历获取A-Z数组

String.fromCharCode(65) === 'A';

String.fromCharCode(90) === 'Z';

let letterArr = [];

for(let i = 65; i< 91; i++) {

letterArr.push(String.fromCharCode(i))

};

 

letterArr结果值：["A", "B", "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M", "N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"];

let dataList = [
    {name: '北京', pinyin: 'beijing'},
    {name: '郑州', pinyin: 'zhengzhou'},
    {name: '武汉', pinyin: 'wuhan'},
];

let newDataList = [];

for(let j=0; j< letterArr.length; j++){
    let arr = dataList.filter(item => 
                item.pinyin.substring(0,1)===letterArr[j].toLowerCase());
    if(arr.length > 0) {
        newDataList.push({
            index: letterArr[j],
            list: arr 
        })
   }
}