lodash / js: Filtering values within an object based on regular expressions and getting the highest by comparison

Question

For the following json

[
  {       
    "index": "xyz",
    ...
  },
  {       
    "index": "abc1234",
    ...
  },
  {       
    "index": "xyz",
    ...
  },
  {       
    "index": "abc5678",
    ...
  }
 ...

I want to filter out abc values and xyz values separately.

I tried the following to get values

  var x = _.filter(jsonData, function (o) { 
      return /abc/i.test(o.index); 
  });

and it worked to give the filtered outputs.

Now i want to get the highest of abc values that is if there values abc123, abc444, abc999 then the code should return abc999.

I can loop over again using lodash but could this be done in a single call - within the same one that filters out?

Answer 1

You can use Array.prototype.reduce(), String.prototype.replace() with RegExp /\D+/ to match and remove characters that are not digits. Check if previous number portion of string is less than current number portion of string

var jsonData = [
  {       
    "index": "xyz",
  },
  {       
    "index": "abc1234",
  },
  {       
    "index": "xyz",
  },
  {       
    "index": "abc5678",
  },
  {       
    "index": "abc1",
  }];

  var x = jsonData.reduce(function (o, prop) { 
           return /abc/i.test(prop.index) 
                  ? !o || +prop.index.replace(/\D+/, "") > +o.replace(/\D+/, "")
                    ? prop.index
                    : o
                  : o
          }, 0);
  
  console.log(x);