我想向数组添加一个值，尝试使用拼接，但它需要工作吗？答案

【问题标题】：I want to add an value to an array, trying using splice, but it want work?我想向数组添加一个值，尝试使用拼接，但它需要工作吗？
【发布时间】：2021-01-25 10:24:04
【问题描述】：

我无法让 splice 为我的 /home 工作。

我显然做错了什么，但我不知道是什么，请帮忙？

const logArray = [
  "|timestamp              |url           |userid|",
  "|2019-03-01 09:00:00UTC |/contact.html |12345 |",
  "|2019-03-01 09:00:00UTC |/contact.html |12346 |",
  "|2019-03-01 10:00:00UTC |/contact.html |12345 |",
  "|2019-03-01 10:30:00UTC |/home.html    |12347 |",
  "|2019-03-01 11:00:00UTC |/contact.html |12347 |",
  "|2019-03-02 11:00:00UTC |/contact.html |12348 |",
  "|2019-03-02 12:00:00UTC |/home.html    |12348 |",
  "|2019-03-03 13:00:00UTC |/home.html    |12349 |",
  ""
];

let result = [];

const urls = () => {
  const url = logArray.map((Objects, index, arr) => {
    return Objects.slice(25, 38);
  });
  console.log("url:", url);
  if (url) {
    const contact = url.find((a) => a.includes("contact"));
    result.push(contact);
    console.log(contact);
    //console.log(contact)
  }
  if (url) {
    const home = url.find((a) => a.includes("home"));
    result.splice(3, 0, home);
    console.log(home);
  }
};
urls();
console.log(result);

我计算了每个 url 上的唯一用户 ID，没有。每个网址的访问次数。

所以我把这个数组拿回来了，根本没有拼接？！：

console.log("result:", result); //output ["/contact.html", "/home.html   ", 5, 4, 1, 1]

这是我想要的样子：

// dream scenario: ["/contact.html", 5, 4, "/home.html", 1, 1]

当我从代码中取出拼接功能并在 codepen 中尝试它时，它工作正常......但不是在完整代码中

【问题讨论】：

您的代码不会产生该输出。我将您的代码移到了 sn-p 中，以便它可以运行。 result 中没有存储任何号码。请确保我们可以重现您提出的问题。

标签： javascript arrays splice array-splice

【解决方案1】：

在我看来，这不是解析日志数据的最佳变体，但如果您愿意的话。这就是解决方案



const logArray = [
  "|timestamp              |url           |userid|",
  "|2019-03-01 09:00:00UTC |/contact.html |12345 |",
  "|2019-03-01 09:00:00UTC |/contact.html |12346 |",
  "|2019-03-01 10:00:00UTC |/contact.html |12345 |",
  "|2019-03-01 10:30:00UTC |/home.html    |12347 |",
  "|2019-03-01 11:00:00UTC |/contact.html |12347 |",
  "|2019-03-02 11:00:00UTC |/contact.html |12348 |",
  "|2019-03-02 12:00:00UTC |/home.html    |12348 |",
  "|2019-03-03 13:00:00UTC |/home.html    |12349 |",
  ""
];

function getDataFromLogs(logs) {
  const formattedLogs = logs.slice(1, logs.length - 1)
  const urls = {}

    formattedLogs.map(log => {
    const route = log.slice(25, 38);
    const userID = log.slice(40, 46);
  
    if (urls[route] === undefined) {
            urls[route] = []
    }
    urls[route].push(userID)
  })
  
  const results = [];
  
  Object.keys(urls).map(key => {
    const data = urls[key];
    results.push(key.trim(), data.length, [...new Set(data)].length);
  })
  
  return results;
}
// ["/contact.html", 5, 4, "/home.html", 3, 3]
console.log(getDataFromLogs(logArray))

【讨论】：

【解决方案2】：

这些是解决方案中的以下步骤 -

通过Array.prototype.slice跳过标题行
按分隔符分割|
统计url键
根据url键累加对象
现在累积后，计算存储在 items.length 中的累积条目数，对于不同的 userId，使用一个集合来计算它。
使用Array.prototype.flat 展平结构以满足您想要的结果

const logArray = [
  "|timestamp              |url           |userid|",
  "|2019-03-01 09:00:00UTC |/contact.html |12345 |",
  "|2019-03-01 09:00:00UTC |/contact.html |12346 |",
  "|2019-03-01 10:00:00UTC |/contact.html |12345 |",
  "|2019-03-01 10:30:00UTC |/home.html    |12347 |",
  "|2019-03-01 11:00:00UTC |/contact.html |12347 |",
  "|2019-03-02 11:00:00UTC |/contact.html |12348 |",
  "|2019-03-02 12:00:00UTC |/home.html    |12348 |",
  "|2019-03-03 13:00:00UTC |/home.html    |12349 |",
  ""
];

const result = Object.entries(logArray
.slice(1)
.reduce((acc, curr) => {
    if (curr) {
        let [,, url, userId] = curr.trim().split('|');
        url = url.trim();
        userId = userId.trim();
        
        acc[url] = (acc[url] || []).concat({
                url,
                userId
        });
    }
    
    return acc;
}, Object.create(null)))
.reduce((r, c) => {
    const [key, items] = c;
    const distinctItemCount = new Set(items.map(x => x.userId)).size;
    r.push([key, items.length, distinctItemCount]);
    return r;
}, [])
.flat();

console.log(result);

【讨论】：