Is there better way than write match very much?

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HI, i have this code

let key = N001DSC29MC22HC22DD04MD09YD21
function get(key) {
  let res = {};
  res.matchNumber = key.match(/(?<=N)\d{3}/g);
  res.matchSeconds = key.match(/(?<=DSC)\d{2}/g);
  res.matchMinutes = key.match(/(?<=MC)\d{2}/g);
  res.matchHours = key.match(/(?<=HC)\d{2}/g);
  res.matchDay = key.match(/(?<=DD)\d{2}/g);
  res.matchMonth = key.match(/(?<=MD)\d{2}/g);
  res.matchYear = key.match(/(?<=YD)\d{2}/g);
  res.title = JSON.parse(localStorage.getItem(key)).title;
  res.description = JSON.parse(localStorage.getItem(key)).description;
  Object.keys(res).forEach(key => {
    if (! res[key]) delete res[key]
    if (Array.isArray(res[key])) res[key] = res[key].join('')
  })
  return res;
}
get(key)

As you can see my code not clean, there is any better way to do the same function. I really try and i can't do better

I Mean there is better from using REGEXP And match very mush Like this

coding-style javascript
2 Answers

In my opinion, you can put the initialization of the object fields inline with the creation of the object, and foreach is not the best to do side effect, try to make object const and use something like filter and reduce:

// the snipped won't work because of the sandbox policy
let key = 'N001DSC29MC22HC22DD04MD09YD21';
function get(key) {
  const res = {
    matchNumber : key.match(/(?<=N)\d{3}/g),
    matchSeconds : key.match(/(?<=DSC)\d{2}/g),
    matchMinutes : key.match(/(?<=MC)\d{2}/g),
    matchHours : key.match(/(?<=HC)\d{2}/g),
    matchDay : key.match(/(?<=DD)\d{2}/g),
    matchMonth : key.match(/(?<=MD)\d{2}/g),
    matchYear : key.match(/(?<=YD)\d{2}/g),
    title : JSON.parse(localStorage.getItem(key)).title,
    description : JSON.parse(localStorage.getItem(key)).description,
  };
  return Object.entries(res)
    .filter(([k]) => k)
    .reduce((acc, [k,v]) => (acc[k] = v, acc), {})
}
get(key)

However, you can actually just avoid creating the res object and start with another data structure (the one that Object.entries will return)

let key = 'N001DSC29MC22HC22DD04MD09YD21';
function get(key) {
  return [
    ['matchNumber' , key.match(/(?<=N)\d{3}/g)],
    ['matchSeconds' , key.match(/(?<=DSC)\d{2}/g)],
    ['matchMinutes' , key.match(/(?<=MC)\d{2}/g)],
    ['matchHours' , key.match(/(?<=HC)\d{2}/g)],
    ['matchDay' , key.match(/(?<=DD)\d{2}/g)],
    ['matchMonth' , key.match(/(?<=MD)\d{2}/g)],
    ['matchYear' , key.match(/(?<=YD)\d{2}/g)],
    ['title' , JSON.parse(localStorage.getItem(key)).title],
    ['description' , JSON.parse(localStorage.getItem(key)).description],
  ].filter(([k]) => k).reduce((acc, [k,v]) => (acc[k] = v, acc), {})
}
get(key)

user_123617000

Creating an Object using Object.fromEntries, where entries are filtered and mapped from Object.entries looks a bit cleaner.

console.log(get(`N001DSC29MC22HC22DD04MD09YD21`));

function get(key) {
 return Object.fromEntries(
  Object.entries({
      matchNumber: key.match(/(?<=N)\d{3}/g),
      matchSeconds: key.match(/(?<=DSC)\d{2}/g),
      matchMinutes: key.match(/(?<=MC)\d{2}/g),
      matchHours: key.match(/(?<=HC)\d{2}/g),
      matchDay: key.match(/(?<=DD)\d{2}/g),
      matchMonth: key.match(/(?<=MD)\d{2}/g),
      matchYear: key.match(/(?<=YD)\d{2}/g),
      // mockup for not working localStorage in sandbox   
      title: `sometitle`,
      description: `somedescription`,
    })
    // filter only key-value pairs with a value
    .filter( ([key, value]) => value )
    // map to values with joined Arrays if applic.
    .map( ([key, value]) => 
      [key, Array.isArray(value) ? value.join('') : value ] )
  );
}

Alternative, labels and regexes from one raw string, using one reducer to create the object.

const getValuesFromKey = key => ({ 
    ...String.raw`
      ID::(?<=N)\d{3}
      Seconds::(?<=DSC)\d{2}
      Minutes::(?<=MC)\d{2}
      Hours::(?<=HC)\d{2}
      Day::(?<=DD)\d{2}
      Month::(?<=MD)\d{2}
      NoMatch::(?<=NOTHING)\d{2} // won't match anything
      Years::(?<=YD)\d{2} // will find two years `
    .split(`\n`)
    .reduce( (acc, line) => {
      line = line.replace(/\/\/.*$/, ``).trim();
      const [label, re] = line && line.split(`::`);
      const match = re && key.match(new RegExp(re, `g`));
      return match ? {...acc, [[label]]: match.join(` and `)} : acc;
    }, {}),
    Title: `someTitle`,
    Description: `someDescription` });

console.log(getValuesFromKey(`N001DSC29MC22HC22DD04MD09YD21YD45`));
//                                                         ^ extra value

Or use named capture groups. See this stackblitz project

NICon_581860
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