Merge random elements of array/split into chunks - arrays

Question

How can I split array into chunks with some special algorithm? E.g. I need to shorten array to the size of 10 elements. If I have array of 11 elements, I want two next standing elements get merged. If I have array of 13 elements, I want three elements merged. And so on. Is there any solution?
Sample #1
var test = ['1','2','3','4','5','6','7','8','9','10','11'];
Need result = [['1'],['2'],['3'],['4'],['5|6'],['7'],['8'],['9'],['10'],['11']]
Sample #2
var test = ['1','2','3','4','5','6','7','8','9','10','11','12','13'];
Need result = [['1|2'],['3'],['4'],['5'],['6'],['7|8'],['9'],['10'],['11'],['12|13']]
Thank you in advance.

Answer 1

The following code most probably does what you want.
function condense(a){
var source = a.slice(),
len = a.length,
excessCount = (len - 10) % 10,
step = excessCount - 1 ? Math.floor(10/(excessCount-1)) : 0,
groupSize = Math.floor(len / 10),
template = Array(10).fill()
.map((_,i) => step ? i%step === 0 ? groupSize + 1
: i === 9 ? groupSize + 1
: groupSize
: i === 4 ? groupSize + 1
: groupSize);
return template.map(e => source.splice(0,e)
.reduce((p,c) => p + "|" + c));
}
var test1 = ['1','2','3','4','5','6','7','8','9','10','11'],
test2 = ['1','2','3','4','5','6','7','8','9','10','11','12','13','14','15','16','17','18','19','20','21'];
console.log(condense(test1));
console.log(condense(test2));

Answer 2

A - Find the difference and create thus many random numbers for merge and put in array
B - loop through initial numbers array.
B1 - if iterator number is in the merge number array (with indexOf), you merge it with the next one and increase iterator (to skip next one as it is merged and already in results array)
B1 example:
int mergers[] = [2, 7, 10]
//in loop when i=2
if (mergers.indexOf(i)>-1) { //true
String newVal = array[i]+"|"+array[i+1]; //will merge 2 and 3 to "2|3"
i++; //adds 1, so i=3. next loop is with i=4
}
C - put new value in results array

Answer 3

You can try this code
jQuery(document).ready(function(){
var test = ['1','2','3','4','5','6','7','8','9','10','11','12','13','14','15','16'];
var arrays = [];
var checkLength = test.length;
var getFirstSet = test.slice(0,10);
var getOthers = test.slice(10,checkLength);
$.each( getFirstSet, function( key,value ) {
if(key in getOthers){
values = value +'|'+ getOthers[key];
arrays.push(values);
}else{
arrays.push(value);
}
});
console.log(arrays);
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>