JavaScript: Find the unique elements from two arrays

JavaScript Array: Exercise-42 with Solution

Write a JavaScript function to find the unique elements from two arrays.

Test Data :
console.log(difference([1, 2, 3], [100, 2, 1, 10]));
["1", "2", "3", "10", "100"]
console.log(difference([1, 2, 3, 4, 5], [1, [2], [3, [[4]]],[5,6]]));
["1", "2", "3", "4", "5", "6"]
console.log(difference([1, 2, 3], [100, 2, 1, 10]));
["1", "2", "3", "10", "100"]

Pictorial Presentation:

Sample Solution:

JavaScript Code :

function difference(arr1,arr2) {
  
  var a1= flatten(arr1,true);
  var a2= flatten(arr2,true);
  
 var a=[], diff=[];
  for(var i=0;i< a1.length;i++)
    a[a1[i]]=false;
  for(i=0;i< a2.length;i++)
  if(a[a2[i]]===true) 
     { delete a[a2[i]];}
    else a[a2[i]]=true;
  for(var k in a)
    diff.push(k);
  return diff;   
  }

var flatten = function(a, shallow,r){
  if(!r){ r = [];}
if (shallow) {
  return r.concat.apply(r,a);
  }  
   for(i=0; i< a.length; i++){
        if(a[i].constructor == Array){
            flatten(a[i],shallow,r);
        }else{
            r.push(a[i]);
        }
    }
    return r;
};
console.log(difference([1, 2, 3], [100, 2, 1, 10]));
console.log(difference([1, 2, 3, 4, 5], [1, [2], [3, [[4]]],[5,6]]));
console.log(difference([1, 2, 3], [100, 2, 1, 10]));

Sample Output:

["1","2","3","10","100"]
["1","2","3","4","5","6"]
["1","2","3","10","100"]

Flowchart :

ES6 Version:

function difference(arr1,arr2) {
  const a1= flatten(arr1,true);
  const a2= flatten(arr2,true);

  const a=[];
  const diff=[];
  for(var i=0;i< a1.length;i++)
    a[a1[i]]=false;
  for(i=0;i< a2.length;i++)
  if(a[a2[i]]===true) 
     { delete a[a2[i]];}
    else a[a2[i]]=true;
  for(const k in a)
    diff.push(k);
  return diff;
}

var flatten = (a, shallow, r) => {
  if(!r){ r = [];}
if (shallow) {
  return r.concat(...a);
  }  
   for(i=0; i< a.length; i++){
        if(a[i].constructor == Array){
            flatten(a[i],shallow,r);
        }else{
            r.push(a[i]);
        }
    }
    return r;
};
console.log(difference([1, 2, 3], [100, 2, 1, 10]));
console.log(difference([1, 2, 3, 4, 5], [1, [2], [3, [[4]]],[5,6]]));
console.log(difference([1, 2, 3], [100, 2, 1, 10]));

Live Demo :

See the Pen JavaScript -Find the unique elements from two arrays-array-ex- 42 by w3resource (@w3resource) on CodePen.

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