How to remove one subset from an array in JS?

Question

Let's say I have an array such as: [1, 1, 2, 2, 3, 3, 4, 5]
And I want to remove this array of elements [1, 2, 3, 4, 5]
So in the end I want to be left with [1, 2, 3]

I have tried using the method below but it removes all copies of the elements from the main array.

myArray = myArray.filter( function( el ) {
  return !toRemove.includes( el );
} );

Answer 1

You could get a Map and count the values and filter by checking the count and decrement the count if found.

 var array = [1, 1, 2, 2, 3, 3, 4, 5], remove = [1, 2, 3, 4, 5], map = remove.reduce((m, v) => m.set(v, (m.get(v) || 0) + 1), new Map), result = array.filter(v => !map.get(v) || !map.set(v, map.get(v) - 1)); console.log(result); 

Answer 2

Here is a way to do it using filter , indexOf and splice .

 const input = [1, 1, 2, 2, 3, 3, 4, 5]; function removeSubset(arr, subset) { const exclude = [...subset]; return arr.filter(x => { const idx = exclude.indexOf(x); if (idx >= 0) { exclude.splice(idx, 1); return false; } return true; }); } console.log(removeSubset(input, [1, 2, 3, 4, 5])); 

Answer 3

You can use Filter and Shitf and Sort

 let arr = [1, 1, 2, 2, 3, 3, 4, 5] let remove = [1, 3, 2, 4, 5].sort((a,b)=>ab) let op = arr.sort((a,b)=>ab).filter(e => ( remove.includes(e) ? (remove.shift(), false) : true )) console.log(op) 

Answer 4

One solution is looping on the array of elements to remove and for each one remove the first element found on the input array:

 const input = [1, 1, 2, 2, 3, 3, 4, 5]; const removeItems = (input, items) => { // Make a copy, to not mutate the input. let clonedInput = input.slice(); // Search and remove items. items.forEach(x => { let i = clonedInput.findIndex(y => y === x); if (i >= 0) clonedInput.splice(i, 1); }); return clonedInput; } console.log(removeItems(input, [1,2,3,4,5])); console.log(removeItems(input, [1,2])); console.log(removeItems(input, [1,99,44,5])); 

If you still want to use filter, you can use the items to remove as the this argument of the filter, something like this:

 const input = [1, 1, 2, 2, 3, 3, 4, 5]; const removeItems = (input, items) => { return input.filter(function(x) { let i = this.findIndex(y => y === x); return i >= 0 ? (this.splice(i, 1), false) : true; }, items.slice()); } console.log(removeItems(input, [1,2,3,4,5])); console.log(removeItems(input, [1,2])); console.log(removeItems(input, [1,99,44,5]));