How to separate each sub group in main group Array using javascript

Question

I have an Array. It contains several subgroups. Example:

let mainArray=[50,51,52,53,54,511,512,513,514,521,522,523,524,525,526,527]

I want

Answer 1

Use the Array reduce function :

let mainArray=[50,51,52,53,54,511,512,513,514,521,522,523,524,525,526,527];

let groups = mainArray.reduce ( 
  (grps, el, i, main) => ((el === main[i-1] + 1 ? grps[0].push (el)
                                                : grps.unshift ([el])), grps), []);

[sub3, sub2, sub1] = groups;

console.log (sub1, sub2, sub3);