试图在javascript中匹配字符串中的年份答案

【问题标题】：Trying to match the year in a string in javascript试图在javascript中匹配字符串中的年份
【发布时间】：2018-12-20 23:41:44
【问题描述】：

我希望能够获取一个字符串数组：

这是我正在使用的模拟数据。

const archives = {
    "data": [{
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Employee Engagement Summary",
                "description": "Report description goes here",
                "creation_date": "March 21, 2018",
                "date_range": "03/01/2018-05/15/2018",
                "data_sets": "Facility A, Nursing Department"
            }
        },
        {
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Sample Survey 1",
                "description": "Report description goes here",
                "creation_date": "March 21, 2017",
                "date_range": "03/01/2017-05/15/2017",
                "data_sets": "Facility A, Nursing Department"
            }
        },
        {
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Sample Survey 2",
                "description": "Report description goes here",
                "creation_date": "March 21, 2016",
                "date_range": "03/01/2016-05/15/2016",
                "data_sets": "Facility A, Nursing Department"
            }
        },
        {
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Sample Survey 3",
                "description": "Report description goes here",
                "creation_date": "March 21, 2015",
                "date_range": "03/01/2015-05/15/2015",
                "data_sets": "Facility A, Nursing Department"
            }
        }
    ]
};

export default archives;

上面的代码拥有我正在使用的真实模拟数据。

然后从中提取年份。因为我希望能够遍历这些年并将它们放在一个列表中

<ul>
  <li>2018</li>
  <li>2017</li>
  <li>2016</li>
  <li>2015</li>
  <li>2014</li>
  <li>2013</li>
  <li>2012</li>
</ul>

【问题讨论】：

请发布您的代码。
第 3 行的附加 f 是错字吗？
有时候会很无聊……例如就像这里一样，所有答案都被否决了，没有真正的解释。这与 SO 的否决权有何关系，他说：“应为极端情况保留否决权。它不能代替沟通和编辑。与其否决票：如果有问题，请留下一个评论或编辑帖子以更正它。”
见Should “Give me a regex that does X” questions be closed?
@Bucket 我发布了我正在使用的实际模拟数据。

标签： javascript html json regex

【解决方案1】：

var str = [
  "March 21, 2018",
  "March 21, 2017f",
  "March 21, 2016",
  "March 21, 2015",
  "March 21, 2014",
  "March 21, 2013",
  "March 21, 2012"
]; 

//Array to hold the years
let years = [];

//Iterate your date collection
for(let i = 0; i < str.length; i++){
    //Split the string on the comma
    const splitter = str[i].split(",");

    //If the split produces more than one string value, meaning we have a formatted date
    if(splitter.length > 1){
       //Replace any non digit characters and trim whitespace
       let year = splitter[1].replace(/\D/g,'').trim();
       //push year value into new array
       years.push(year);

    }
}

//View the results in console
console.log(years);

【讨论】：

【解决方案2】：

如果您的字符串始终采用相同的格式，您可以在 , 上进行拆分。我使用正则表达式/[^0-9]/gi 将年份中不是数字的任何内容替换为非字符''。这可以防止像 2017f 这样的东西包含 f.

var dates = [
  "March 21, 2018",
  "March 21, 2017f",
  "March 21, 2016",
  "March 21, 2015",
  "March 21, 2014",
  "March 21, 2013",
  "March 21, 2012"
]; 

const years = [];
for(const date of dates){
  const year = date.split(',')[1].replace(/[^0-9]/gi, '').trim();
  years.push(year);
}

console.log(years);

【讨论】：

【解决方案3】：

至少匹配四位数字，至少对于您的情况

(str => str.match(/\d{4}/)[0])

var dateStrings = [
  "March 21, 2018",
  "March 21, 2017f",
  "March 21, 2016",
  "March 21, 2015",
  "March 21, 2014",
  "March 21, 2013",
  "March 21, 2012"
];
var years = dateStrings.map(str => str.match(/\d{4}/)[0]);
var ul = years.reduce((ul, year) => {
  var li = document.createElement('li');
  li.innerHTML = year;
  ul.appendChild(li);
  return ul;
}, document.createElement('ul'));

document.body.appendChild(ul);

【讨论】：

是的，几乎一样
比其他人建议的要容易得多
@JuanMendes 那么，做 2 个循环，一个 map 然后一个 forEach 怎么这么容易呢？ ...在我的情况下，我只使用一个循环，效率更高。
@LGSon 要点是正则表达式，4 位数字真的很容易阅读，并且不需要您匹配两件事（假设更多关于输入）。这与效率无关，而是看代码的难易程度。我在这里没有看到任何性能瓶颈，我认为函数式编程的优雅不会让您付出任何明显的代价。但同样，这不是问题的重点。 “尝试在 javascript 中匹配字符串中的年份”
@JuanMendes 鉴于这里的用户将接受一个答案赞成/工作的代码，并在他们自己的代码中使用它，这可能很重要，做 2 个循环，那么为什么要奖励它呢？跨度>

【解决方案4】：

使用匹配项并检查 4 位数字：/\d{4}/

var str = [
  "March 21, 2018",
  "March 21, 2017f",
  "March 21, 2016",
  "March 21, 2015",
  "March 21, 2014",
  "March 21, 2013",
  "March 21, 2012"
];

let ul = document.querySelector('ul')

str.forEach(date => {
  let matches = date.match(/\d{4}/)
  matches.length > 0 ? (ul.innerHTML += `<li>${matches[0]}</li>`) : null
})

&lt;ul&gt;&lt;/ul&gt;

【讨论】：

Nenad Vracar already posted 相同的答案。此外，它不适用于第二项 "March 21, 2017f"

【解决方案5】：

试试这个：

var archives = {
    "data": [{
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Employee Engagement Summary",
                "description": "Report description goes here",
                "creation_date": "March 21, 2018",
                "date_range": "03/01/2018-05/15/2018",
                "data_sets": "Facility A, Nursing Department"
            }
        },
        {
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Sample Survey 1",
                "description": "Report description goes here",
                "creation_date": "March 21, 2017",
                "date_range": "03/01/2017-05/15/2017",
                "data_sets": "Facility A, Nursing Department"
            }
        },
        {
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Sample Survey 2",
                "description": "Report description goes here",
                "creation_date": "March 21, 2016",
                "date_range": "03/01/2016-05/15/2016",
                "data_sets": "Facility A, Nursing Department"
            }
        },
        {
            "id": 1,
            "type": "archive",
            "attributes": {
                "name": "Sample Survey 3",
                "description": "Report description goes here",
                "creation_date": "March 21, 2015",
                "date_range": "03/01/2015-05/15/2015",
                "data_sets": "Facility A, Nursing Department"
            }
        }
    ]
};

var yearsRange = archives.data.map(obj => obj.attributes.date_range);

var yearArr= [];

yearsRange.filter(item => {
   yearArr.push(item.split('/')[2].split('-')[0]);
});

console.log("yearArr", yearArr);

【讨论】：