Slice and Splice empty array

JavaScript
#1

I do not understand, why array “fr” return empty array?


function frankenSplice(arr1, arr2, n) {
  var a = arr1;
  var b = arr2;
var fr =[];
  
  return fr = b.splice(n, 0, a);
}

frankenSplice([1, 2, 3], [4, 5, 6], 1);

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#2

splice changes the original array so if return b instead of fr you will get your answer

 b.splice(n, 0, a)
   return b

also you could use a spread operator on a

#3

Anyway, gives an error…

function frankenSplice(arr1, arr2, n) {
  var a = arr1;
  var b = arr2;

 b.splice(n, 0, ...a);
 return b;
}

frankenSplice([1, 2, 3], [4, 5, 6], 1);

compilator si writing: ‘The second array should remain the same after the function runs.’

#4

yes because arr2 must stay original so this is where slice comes in, use slice() to copy the array to another first hope this helps as i dont wanna just write the solution as thats not gonna help you

#5

It worked. Thank you very much for your help.

1 Like
#6