Question

我正在尝试转换看起来像这样的对象数组：

var allApps = [
 {
  title: "amazon",
  summary: "lorem ipsum"
 },
 {
  title: "facebook",
  summary: "lorem ipsum"
 },
 {
  title: "twitter",
  summary: "lorem ipsum"
 },
 {
  title: "flipp",
  summary: "lorem ipsum"
 }
]

变成这样的东西：

var titles= {
A: [
    {      
     title: "amazon",
     summary: "lorem ipsum"
    }
],
F: [
     {
      title: "facebook",
      summary: "lorem ipsum"
     },
     {
      title: "flipp",
      summary: "lorem ipsum"
     }
],
T: [
     {
      title: "twitter",
      summary: "lorem ipsum"
     }
   ]
}

到目前为止，我有这个：

        var letters = [];
        var titles = [];
        for (var i = 0; i < allApps.length; i++) {
            title = allApps[i].title;
            if (title=="") {
                continue;
            }
            var firstLetter = title.substring(0,1);
            var arrayWithFirstLetter = titles[firstLetter];
            if (arrayWithFirstLetter == null) {
                titles[firstLetter] = [];
                letters.push(firstLetter);
            };
        }

我本质上是想根据title属性对应用程序进行排序，然后将它们与相应字母一起推入数组。

现在，我的代码获取每个标题的第一个字母，并为每个字母创建一个数组数组

Answer 1

怎么样：

var allApps = [
 {
  title: "amazon",
  summary: "lorem ipsum"
 },
 {
  title: "facebook",
  summary: "lorem ipsum"
 },
 {
  title: "twitter",
  summary: "lorem ipsum"
 },
 {
  title: "flipp",
  summary: "lorem ipsum"
 }
]

var d = {};
for (var i=0; i<allApps.length; i++) {
  var l = allApps[i].title.substring(0,1);
  // ensure object has key
  if (!d[l]) d[l] = [];
  d[l].push(allApps[i]);
}

console.log(d)

此日志：

{
  a: [
    { title: 'amazon', summary: 'lorem ipsum' }
  ],
  f:[
    { title: 'facebook', summary: 'lorem ipsum' },
    { title: 'flipp', summary: 'lorem ipsum' }
  ],
  t: [
    { title: 'twitter', summary: 'lorem ipsum' }
  ]
}

这里的想法是，我们只需遍历allApps，检查该数组当前成员上title属性的第一个字母，然后检查该字母是否已成为我们新字典{{1 }}。如果不是，我们在d中将该字母添加为键。然后，将d中的当前元素添加到该键的值列表中。就是这样！

Answer 2

使用reduce函数，并从当前对象获得第一个字符。第一个角色将是。如果该密钥存在，则更新其值

var allApps = [{
    title: "amazon",
    summary: "lorem ipsum"
  },
  {
    title: "facebook",
    summary: "lorem ipsum"
  },
  {
    title: "twitter",
    summary: "lorem ipsum"
  },
  {
    title: "flipp",
    summary: "lorem ipsum"
  }
]
let k = allApps.reduce(function(acc, curr) {
  let getFirstChar = curr.title.charAt(0).toUpperCase();

  if (acc[getFirstChar] === undefined) {
    acc[getFirstChar] = [];
  }
  acc[getFirstChar].push(curr)
  return acc;



}, {})
console.log(k)

Answer 3

您不需要变量letters。您应该使用titles[firstletter]。

titles应该初始化为对象，而不是数组。

var allApps = [
 {
  title: "amazon",
  summary: "lorem ipsum"
 },
 {
  title: "facebook",
  summary: "lorem ipsum"
 },
 {
  title: "twitter",
  summary: "lorem ipsum"
 },
 {
  title: "flipp",
  summary: "lorem ipsum"
 }
];

var titles = {};
for (var i = 0; i < allApps.length; i++) {
  title = allApps[i].title;
  if (title == "") {
    continue;
  }
  var firstLetter = title.substring(0, 1).toUpperCase();
  if (!titles[firstLetter]) {
    titles[firstLetter] = [];
  };
  titles[firstLetter].push(allApps[i]);
}

console.log(titles);

取对象数组并按字母顺序排序成较小的数组

3 个答案: