按索引删除多个数组元素并存储删除的元素

Question

How can I remove multiple items by index and save the removed items. I get the currently selected values from a ListBox (eg selectedValues = [1, 4, 2] ) and have two arrays actives availables . I try to move the selected elements in an efficient way.

That's how I would solve this:

 var actives = [ "a", "d", "k", "e"] var availables = [ "m", "o", "v" ] var selectedValues = [3, 1] var elementsToMove = [] selectedValues.forEach(i => { elementsToMove.push(actives[i]) }) actives = actives.filter(item => !elementsToMove.includes(item)) availables = availables.concat(elementsToMove); console.log(actives); console.log(availables);

Expected output:

actives = [ "a", "k" ]
availables = [ "m", "o", "v", "e", "d"] 

Note: The length of the arrays can be very large.

Answer 1

A .filter with an .includes inside is O(n ^ 2) . For very large inputs, this could be an issue. Consider converting the elementsToMove into a Set instead, turning the overall computational complexity to O(n) . You can also construct the elementsToMove array much more concisely by using .map instead of forEach followed by push :

 var actives = [ "a", "d", "k", "e"] var availables = [ "m", "o", "v" ] var selectedValues = [3, 1]; const elementsToMove = selectedValues.map(i => actives[i]); const elementsToMoveSet = new Set(elementsToMove); actives = actives.filter(item => !elementsToMoveSet.has(item)) availables = availables.concat(elementsToMove); console.log(actives); console.log(availables);

Answer 2

You could take a single loop and psuh the spliced elements to the other array.

 var actives = [ "a", "d", "k", "e"], availables = [ "m", "o", "v" ], selectedValues = [3, 1]; selectedValues.forEach(i => availables.push(...actives.splice(i, 1))); console.log(actives); console.log(availables);