Question

考虑以下数组：

[
  { url: "https://url.com/file1", md5: "fbbbabcc19264ce7b376ce4c726b9b85" },
  { url: "https://url.com/file2", md5: "d920d140432b961f07695ec34bd2a8ad" },
  { url: "https://url.com/file3", md5: "fbbbabcc19264ce7b376ce4c726b9b85" },
  { url: "https://url.com/file4", md5: "bf80655dbe90123324f88a778efa39f7" },
  { url: "https://url.com/file5", md5: "fbbbabcc19264ce7b376ce4c726b9b85" }
];

文件“ file1”，“ file3”和“ file5”具有相同的内容，因此具有相同的md5。我只想使用不同的md5（文件1，文件2，文件4）保留文件。

使用现代ES6有哪些可能的方法？

Answer 1

public class dbtesting {

  private static Connection connection = null;

  def connection(String server, String port, String dbname, String username, String password) {
    String url = "jdbc:sqlserver://" + server + ":" + port + ";databaseName=" + dbname + ";user=" + username + ";password=" + password + ";IntegratedSecurity=true"
    connection = DriverManager.getConnection(url)
  }
}

您可以通过特定键（在您的情况下为“ md5”）过滤数组。

Answer 2

您可以使用Set来跟踪已找到的文件。

const arr = [{
    url: 'https://url.com/file1',
    md5: 'fbbbabcc19264ce7b376ce4c726b9b85'
  },
  {
    url: 'https://url.com/file2',
    md5: 'd920d140432b961f07695ec34bd2a8ad'
  },
  {
    url: 'https://url.com/file3',
    md5: 'fbbbabcc19264ce7b376ce4c726b9b85'
  },
  {
    url: 'https://url.com/file4',
    md5: 'bf80655dbe90123324f88a778efa39f7'
  },
  {
    url: 'https://url.com/file5',
    md5: 'fbbbabcc19264ce7b376ce4c726b9b85'
  }
]

const uniqueFiles = new Set();
const ans = arr.filter(ele => {
  if (!uniqueFiles.has(ele.md5)) {
    uniqueFiles.add(ele.md5);
    return true;
  }
  return false;
});

console.log(ans)

Answer 3

您可以使用reduce解决问题：

const list = [
    { url: 'https://url.com/file1', md5: 'fbbbabcc19264ce7b376ce4c726b9b85' },
    { url: 'https://url.com/file2', md5: 'd920d140432b961f07695ec34bd2a8ad' },
    { url: 'https://url.com/file3', md5: 'fbbbabcc19264ce7b376ce4c726b9b85' },
    { url: 'https://url.com/file4', md5: 'bf80655dbe90123324f88a778efa39f7' },
    { url: 'https://url.com/file5', md5: 'fbbbabcc19264ce7b376ce4c726b9b85' },
];

const removeDup = (arr, key) => {
    return arr.reduce((acc, cur) => {
        if (acc.some(a => a[key] === cur[key])) return acc;
        return acc.concat(cur)
    }, [])
};

console.log(removeDup(list, 'md5'))

Answer 4

只需使用以md5散列为键的映射：

const md5_map =
  files =>
    files.reduce((map, {url, md5}) =>
      ({...map, [md5]: url}), {});
      
console.log(md5_map(files));

<script>
const files = [
  { url: "https://url.com/file1", md5: "fbbbabcc19264ce7b376ce4c726b9b85" },
  { url: "https://url.com/file2", md5: "d920d140432b961f07695ec34bd2a8ad" },
  { url: "https://url.com/file3", md5: "fbbbabcc19264ce7b376ce4c726b9b85" },
  { url: "https://url.com/file4", md5: "bf80655dbe90123324f88a778efa39f7" },
  { url: "https://url.com/file5", md5: "fbbbabcc19264ce7b376ce4c726b9b85" }
]
</script>

Answer 5

const list = [
  { url: 'https://url.com/file1', md5: 'fbbbabcc19264ce7b376ce4c726b9b85' },
  { url: 'https://url.com/file2', md5: 'd920d140432b961f07695ec34bd2a8ad' },
  { url: 'https://url.com/file3', md5: 'fbbbabcc19264ce7b376ce4c726b9b85' },
  { url: 'https://url.com/file4', md5: 'bf80655dbe90123324f88a778efa39f7' },
  { url: 'https://url.com/file5', md5: 'fbbbabcc19264ce7b376ce4c726b9b85' },
];

const deDupe = (arr = []) => {
  return Object.values(arr.reduce((obj, item) => {
    obj[item.md5] = obj[item.md5] || item;
    return obj;
  }, {}));
}

const dedupedList = deDupe(list);

console.log(dedupedList);

/* 
  [
    {
      "url": "https://url.com/file1",
      "md5": "fbbbabcc19264ce7b376ce4c726b9b85"
    },
    {
      "url": "https://url.com/file2",
      "md5": "d920d140432b961f07695ec34bd2a8ad"
    },
    {
      "url": "https://url.com/file4",
      "md5": "bf80655dbe90123324f88a778efa39f7"
    }
  ] 
*/

如何在JavaScript对象列表中按键值删除重复项？

5 个答案: