JS filtering array using regexp on value

Question

I have arr with categories tree. Example: category yy is subcategory of ww and ww is subcategory of zz. I want to filter this array and get this output: ['aa_bb', 'aa_cc', 'zz_ww_yy']. So I don't want zz and zz_ww becouse i have this in zz_ww_yy. I think that I must use filter function and maybe some regexp? hmmm and maybe foreach? What you think?

var arr = ['aa_bb', 'aa_cc', 'aa', 'zz', 'zz_ww','zz_ww_yy'];

var filtered = arr.filter(function(a){
    //???
})

console.log(filtered);

Welcome to Stack Overflow! Please take the tour and read through the help center, in particular How do I ask a good question? Do your research, search for related topics on SO, and give it a go. (You're likely to need two passes through the array, and regex probably isn't much help here.) If you get stuck and can't get unstuck after doing more research and searching, post a minimal reproducible example of your attempt and say specifically where you're stuck. People will be glad to help. Good luck! — T.J. Crowder
– T.J. Crowder, Commented Dec 31, 2017 at 12:26

Nina Scholz · Accepted Answer · 2017-12-31 12:56:55Z

2

You could take String#indexOf and filter the temporary result array with the given string.

Then check if the string is not a substring of the result set and push it if not.

var array = ['aa_bb', 'aa_cc', 'aa', 'zz', 'zz_ww','zz_ww_yy'],
    result = array.reduce(function (r, a) {
        r = r.filter(b => a.indexOf(b) === -1);
        if (r.every(b => b.indexOf(a) === -1)) {
            r.push(a);
        }
        return r;
    }, []);
    
console.log(result);

answered Dec 31, 2017 at 12:56

Nina Scholz

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Lafi · Accepted Answer · 2017-12-31 13:43:35Z

0

try that on also, you could easely change the logic.

var arr = ['aa_bb', 'aa_cc', 'aa', 'zz', 'zz_ww', 'zz_ww_yy'];

function shoulFilterCategory(arr, itemToTest, itemIndex) {
  var shouldFilter = false;

  arr.filter((item, index) => index !== itemIndex)
     .forEach(item => {
    if (item.startsWith(itemToTest) && itemToTest.length < item.length)         {
      shouldFilter = true;
    }
  });
  return shouldFilter;
}

var filtered = arr.filter(
  (item, index) => !shoulFilterCategory(arr, item, index)
);

console.log('filtered', filtered);

answered Dec 31, 2017 at 13:43

Lafi

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