CodeWars: Split and Replace, if Needed

CodeWars: Split and Replace, if Needed.txt

ASSIGNMENT
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Complete the solution so that it splits the string into pairs of two characters. 
If the string contains an odd number of characters then it should 
replace the missing second character of the final pair with an underscore ('_').

Examples:

solution('abc') // should return ['ab', 'c_']
solution('abcdef') // should return ['ab', 'cd', 'ef']
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SOLUTION
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function solution(str){
   let re = /[a-z]{1,2}/g;
   let splitted = str.match(re);
   return splitted.map(function(item) { 
     return item.length > 1 ? item : item + '_';
    });   
};
solution('abcdef')

___________________________
it could be shortened: 

function solution(str){
   let re = /[a-z]{1,2}/g;
   return str.match(re).map(function(item) { 
     return item.length > 1 ? item : item + '_';
    });   
};
solution('abcdef')