1the_world_is_flat=true
2# ...do something interesting...
3if [ "$the_world_is_flat" = true ] ; then
4    echo 'Be careful not to fall off!'
5fi

1let difference = arr1.filter(x => !arr2.includes(x));
2

1function diffArray(arr1, arr2) {
2  return arr1
3    .concat(arr2)
4    .filter(item => !arr1.includes(item) || !arr2.includes(item));
5}

1const diffArray = (arr1, arr2) => {
2  // Store the different elements
3  const diffArray = []
4  // Concat both arrays
5  const uniqueArr = [...new Set([...arr1, ...arr2])];
6  // OR const uniqueArr = [...new Set(arr1.concat(...arr2))]
7
8  // Loop through the unique array and confirm that each element in it
9  // is in both arrays(arr1,arr2), else push element not found in both 
10  // arrays to the diffArray and return it
11  uniqueArr.forEach(elem => {
12    if(!arr1.includes(elem) || !arr2.includes(elem))
13      diffArray.push(elem)
14  })
15  return diffArray
16}
17
18diffArray([1, 2, 3, 5], [1, 2, 3, 4, 5]);
19// With love @kouqhar