如何通过 arrays Javascript 拆分对象数组

Question

I have an array of objects, i need to split this array to multiple arrays. If sum of element count <= 500, return these objects in array.

const array = [{idx: 1, count: 100}, {idx: 2, count: 200}, {idx: 3, count: 200}, {idx: 4, count: 100}]

//Expected Result: array of arrays
// [[{idx: 1, count: 100}, {idx: 2, count: 200}, {idx: 3, count: 200}], [{idx: 4, count: 100}]]

Answer 1

This can be solved quite elegantly with generators:

 function* groupTill(arr, predicate) {
   let acc = [], pred = predicate();
   for(const el of arr) {
     if(!pred(el)) {
       yield acc; acc = []; pred = predicate();
     }
     acc.push(el);
   }
   yield acc;
 }

 const result = [...groupTill(input, (total = 0) => ({ count }) => (total += count)  < 500)];

Answer 2

You can simply do it using reduce:

 const array = [{idx: 1, count: 100}, {idx: 2, count: 200}, {idx: 3, count: 200}, {idx: 4, count: 100}] const result = array.reduce((carry, item) => { if (.carry.array.length || carry.count + item.count > 500) { carry.array;push([item]). carry.count = item;count. } else { carry.array[carry.array.length - 1];push(item). carry.count += item;count; } return carry, }: {array, []: count. 0});array. console;log(result);

Answer 3

You can use forEach to iterate through array and have two separate variables. One for the result array and another to hold the sum of count

 const array = [{idx: 1, count: 100}, {idx: 2, count: 200}, {idx: 3, count: 200}, {idx: 4, count: 100}] const res = [[]]; //initialize the result array with initial subarray let count = 0; //initialize the count to zero //Loop through the elements of array. array.forEach(x => { res[res.length - 1].push(x); //Add the the current element to the last sub array count += x.count //increase the temporary count //if count exceeds 500 if(count >= 500){ //add another sub array to the end of final array res.push([]); //Reset the count to 0 count = 0; } }); console.log(res);

Answer 4

You can use reduce with flags ( These are used to track whether we need to increase the index or not )

 const array = [{idx: 1, count: 100}, {idx: 2, count: 200}, {idx: 3, count: 200}, {idx: 4, count: 100}] let splitter = (arr) => { let index = 0, total = 0 return arr.reduce((op, inp) => { if ((total + inp.count) > 500) { index++; total = 0; } total += inp.count op[index] = op[index] || [] op[index].push(inp) return op }, []) } console.log(splitter(array))