CODEWITHSUNDEEP
javascript
user14459580
user14459580

Reputation: 276

How to get a substring in between 2 identical characters in javascript?

So I know how to get a substring from 2 characters using index or split method. But I'm stuck in a scenario of lots of string with similar names such as:

   "2020-12-09-name_of_this_mission_num1_mission1_fileName_something"
   "2020-12-09-name_of_this_mission_num1_mission12_fileName_something"
   "2020-12-09-name_of_this_mission_num23_mission1_fileName_something_else"

Like I am stuck on how to extract just the "mission#" part, because sometimes the names can be different, so the length is different, and sometimes the names are the same, same as the fileName. I also thought about using the index of "_", but there are multiple "_" and they might end up in different index if the name is different.

Could anyone give me some hint on this?

Upvotes: 1

Views: 75

Answers (3)

sideroxylon
sideroxylon

Reputation: 4416

A simple regex match function. Note that 'match' outputs an array, so push match[0]:

const  missions =  [
  "2020-12-09-name_of_this_mission_num1_mission1_fileName_something",
  "2020-12-09-name_of_this_mission_num1_mission12_fileName_something",
  "2020-12-09-name_of_this_mission_num23_mission1_fileName_something_else"
]

let Arr = [];

missions.forEach(function(mission) {
  const missionID = mission.match(/mission\d+/);
  Arr.push(missionID[0]);
})

console.log(Arr);

Upvotes: 2

gavgrif
gavgrif

Reputation: 15489

If the structure of the strings are always the same - and you want the second instance of 'mision' - then split the full string on the text of 'mission'.

This will yield an array with three portions - ["2020-12-09-name_of_this_", "num1", "1_fileName_something"])

Then get the last item in this portions array and grab the number from the start of the resultant string.

Then you can prefix it with the 'mission' that you removed, push it into an array and you have a array of of missions.

If your initial string does not contain a two instances of 'mission' then you can set it to return the 2nd not 3rd portion as I have doen with 'mission2'.

const  missions =  [
  "2020-12-09-name_of_this_mission_num1_mission1_fileName_something",
  "2020-12-09-name_of_this_mission_num1_mission12_fileName_something",
  "2020-12-09-name_of_this_mission_num23_mission1_fileName_something_else",
  "2020-12-09-name_of_this_mission2_fileName_something_else"
]


let missionsArr = [];

missions.forEach(function(mission) {
  const missionPortions = mission.split('mission');
  let index; 
  
  missionPortions.length == 2
    ? index = 1
    : index = 2
    
  missionsArr.push('mission' + parseInt(missionPortions[index]))
})


console.log(missionsArr); //gives ["mission1","mission12", "mission1", "mission2"];

Upvotes: 2

Lars Holdaas
Lars Holdaas

Reputation: 750

Easiest way to just get the mission##, assuming # is a variable number of digits, is by using regex.

The base regex would be /mission\d+/ which matches the string "mission" followed by at least one number.

Assuming you have your input as:

const missionsTexts = [
  "2020-12-09-name_of_this_mission_num1_mission1_fileName_something",
  "2020-12-09-name_of_this_mission_num1_mission12_fileName_something",
  "2020-12-09-name_of_this_mission_num23_mission1_fileName_something_else"
];

You can transform them into an array of just mission# with the following algorithm:

const missions = missionsTexts.map(missionText => missionText.match(/mission\d+/g)[0]);

Note that this assumes there's only one mission# per missionText. The g modifier is used to make sure the regex doesn't create a match after the first digit it finds.

Upvotes: 1

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