Filter strings which doesn't includes strings from other array?

Question

I want to filter an array of urls by excluding ones that contain any substrings that are in a blacklist array.

const urls = [
'http://example.com/people/chuck', 
'http://example.com/goats/sam', 
'http://example.com/goats/billy', 
'http://example.com/goats/linda', 
'http://example.com/cows/mary', 
'http://example.com/cows/betty', 
'http://example.com/people/betty']

const blacklist = ['cows', 'goats']

let cleanUrls = [];

I can do this with for-loops but I want to find a clean/concise way using filter and/or reduce.

If I didn't need to loop over x number of blacklist items:

cleanUrls = urls.filter( url => !url.includes(blacklist[0]) )                  
                .filter( url => !url.includes(blacklist[1]) )

I also don't want to just iterate through the blacklist with a forEach or map because I want to immediately stop if a particular url matches any blacklist entry.

Plain JS please. Thank you. :)

urls.some(url => blacklist.includes(url))

Pavlo
– Pavlo

2018-03-29 17:03:47 +00:00
Commented Mar 29, 2018 at 17:03 — Pavlo
– Pavlo, Commented Mar 29, 2018 at 17:03

Mohammad Usman · Accepted Answer · 2018-03-30 10:28:37Z

7

You can use filter() like this:

const cleanUrls = urls.filter(u => blacklist.every(s => !u.includes(s)));

Or

const cleanUrls = urls.filter(u => !blacklist.some(s => u.includes(s)));

Description:

.includes() will check the existence of a sub-string withing another string.
.every() will check whether none of the strings of blacklist array exists in a particular URL.
.some() will check whether any of the string of blacklist array exists in a particular URL.
.filter() will select only those URL's which will pass the test.

Demo:

const urls = [
  'http://example.com/people/chuck', 
  'http://example.com/goats/sam', 
  'http://example.com/goats/billy', 
  'http://example.com/goats/linda', 
  'http://example.com/cows/mary', 
  'http://example.com/cows/betty', 
  'http://example.com/people/betty'
];

const blacklist = ['cows', 'goats'];

const cleanUrls = urls.filter(u => blacklist.every(s => !u.includes(s)));

console.log(cleanUrls);

Docs:

edited Mar 30, 2018 at 10:28

answered Mar 29, 2018 at 17:04

Mohammad Usman

39.6k20 gold badges99 silver badges101 bronze badges

Sign up to request clarification or add additional context in comments.

4 Comments

Hunter McMillen Over a year ago

I think you mean some not every

Mohammad Usman Over a year ago

@HunterMcMillen Yes, I just thought some but mistakenly wrote another.

Mohammad Usman Over a year ago

To Downvoter: May I know the reason of your downvote?

Mohammad Usman Over a year ago

@HunterMcMillen By the way, every() will work too and it seems more appropriate as compared to some()

Nenad Vracar · Accepted Answer · 2018-03-29 17:05:14Z

1

You can do this with filter(), some() and includes() methods.

const urls = ['http://example.com/people/chuck', 'http://example.com/goats/sam', 'http://example.com/goats/billy', 'http://example.com/goats/linda', 'http://example.com/cows/mary', 'http://example.com/cows/betty', 'http://example.com/people/betty'];
const blacklist = ['cows', 'goats']

const result = urls.filter(url => !blacklist.some(e => url.includes(e)))

console.log(result)

answered Mar 29, 2018 at 17:05

Nenad Vracar

122k16 gold badges160 silver badges184 bronze badges

Comments

Jonas Wilms · Accepted Answer · 2018-03-29 17:07:32Z

0

It might be easuer to turn the blacklist i to a Regex:

 const block = new RegExp(blacklist.join("|"));

Them its as simple as:

 cleanUrls = urls.filter(url => !url.match(block));

answered Mar 29, 2018 at 17:07

Jonas Wilms

139k20 gold badges164 silver badges164 bronze badges

Comments

brk · Accepted Answer · 2018-03-29 17:09:39Z

You can use forEach & indexOf to check if the element from second array is present in the url

const urls = [
  'http://example.com/people/chuck',
  'http://example.com/goats/sam',
  'http://example.com/goats/billy',
  'http://example.com/goats/linda',
  'http://example.com/cows/mary',
  'http://example.com/cows/betty',
  'http://example.com/people/betty'
]

const blacklist = ['cows', 'goats'];

var newArray = [];
blacklist.forEach(function(item) {
  if (newArray.length === 0) {
    newArray = urls.filter(function(items) {
      return (items.indexOf(item) === -1)

    })

  } else {
    newArray = newArray.filter(function(items) {
      return (items.indexOf(item) === -1)
    })
  }
});
console.log(newArray)

Bartłomiej Gładys · Accepted Answer · 2018-03-29 17:17:25Z

I also don't want to just iterate through the blacklist with a forEach or map because I want to immediately stop if a particular url matches any blacklist entry.

The function stop searching if an element from the blacklist appears.

Recursive way to solve this problem:

const urls = [
'http://example.com/people/chuck', 
'http://example.com/goats/sam', 
'http://example.com/goats/billy', 
'http://example.com/goats/linda', 
'http://example.com/cows/mary', 
'http://example.com/cows/betty', 
'http://example.com/people/betty']

const blacklist = ['cows', 'goats']

function filter([url, ...urls] =[], blackList=[], filteredUrls =[] ){
	return !url || blacklist.some(el => url.includes(el)) 
        ? filteredUrls 
        : filter(urls, blackList, [...filteredUrls, url])
}

console.log(filter(urls, blacklist));

amitdigga · Accepted Answer · 2018-03-29 17:19:03Z

Others have answered the question. Providing two different scenarios.

const urls = [
  'http://example.com/people/chuck',
  'http://example.com/goats/billy',
  'http://example.com/aagoatsss/billyyy',
  'http://example.com/people/betty'
]

const blacklist = ['cows', 'goats']

//1st approach. It will also block 'http://example.com/aagoatsss/billyyy'
let cleanUrls1 = urls.filter(
  url => blacklist.find(
    blockWord => url.indexOf(blockWord) != -1 //Url contains Block Word
  ) === undefined //url donot contain any block word.
)

console.log(cleanUrls1)

//2nd approach. It will pass 'http://example.com/aagoatsss/billyyy'

let cleanUrls2 = urls.filter(
  url => blacklist.find(
    blockWord => url.split('/').indexOf(blockWord) != -1 //Url contains Block Word
  ) === undefined //url donot contain any block word.
)
console.log(cleanUrls2)

Collectives™ on Stack Overflow

Filter strings which doesn't includes strings from other array?

6 Answers 6

4 Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

6 Answers 6

4 Comments

Comments

Comments

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related