Js - removing an object array element if value is 0

Question

I have this array object:

0:
  id: "123123"
  cost: 100
  quantity: 2
1:
  id: "112233"
  cost: 100
  quantity: 5
2:
  id: "112233"
  cost: 100
  quantity: 0
3:
  id: "126233"
  cost: 100
  quantity: 0

What I want is to scan the whole object array and delete the ones with 0 quantity value. How do I do this with javascript?

Answer 1

Using the function from my answer at remove objects from array by object property,

filterInPlace(array, item => item.quantity !== 0);

const filterInPlace = (array, predicate) => {
    let end = 0;

    for (let i = 0; i < array.length; i++) {
        const obj = array[i];

        if (predicate(obj)) {
            array[end++] = obj;
        }
    }

    array.length = end;
};

const arr = [
    {
        id: "123123",
        cost: 100,
        quantity: 2,
    },
    {
        id: "112233",
        cost: 100,
        quantity: 5,
    },
    {
        id: "112233",
        cost: 100,
        quantity: 0,
    },
    {
        id: "126233",
        cost: 100,
        quantity: 0,
    },
];

filterInPlace(arr, item => item.quantity !== 0);

console.log(arr);

• This does modify the array in place. If you don’t need that, the Array#filter equivalent is probably better.

• This is linear-time, constant space, whereas solutions based splice have a worse worst case(s). (@Hogan’s answer is also linear-time; this is the same idea as it, but with the loops merged.)

Answer 2

array.filter() creates new array with the filtered objects.

take a look at this:

const values = [
  {id: '123123', cost: 100, quantity: 2},
  {id: '112233', cost: 100, quantity: 5},
  {id: '112233', cost: 100, quantity: 0},
  {id: '126233', cost: 100, quantity: 0},
]

const filtered = values.filter((obj) => obj.quantity !== 0)

console.log(filtered)
// expected output: [ { id: '123123', cost: 100, quantity: 2 }, { id: '112233', cost: 100, quantity: 5 } ]

Answer 3

let data = [
 {id: "123123",
  cost: 100,
  quantity: 2},
 { id: "112233",
  cost: 100,
  quantity: 5}, 
 { id: "112233",
  cost: 100,
  quantity: 0},
 {id: "126233",
  cost: 100,
  quantity: 0} 
];

let i =0;
 while (i < data.length) {
    if (data[i].quantity === 0) {
      data.splice(i, 1);
    } else {
      ++i;
    }
  }

console.table(data);

Answer 4

I usually don't recommend mutating the input itself. But since you have this requirement, Just created this utility in order to fulfil your requirement.

let data = [
  { id: '123123', cost: 100, quantity: 2 },
  { id: '112233', cost: 100, quantity: 5 },
  { id: '112232', cost: 100, quantity: 0 },
  { id: '112234', cost: 200, quantity: 0 },
  { id: '112235', cost: 400, quantity: 1 }
]

const indexesToBeRemoved = [];
data.forEach((d, index) => {
  if(d.quantity === 0) indexesToBeRemoved.push(index)
})

const length = indexesToBeRemoved.length;
for(let i=length-1; i>=0; i--) {
  data.splice(indexesToBeRemoved[i],1)
}

console.log(data)

One another way of fulfilling your requirement.

let data = [
  { id: '123123', cost: 100, quantity: 2 },
  { id: '112233', cost: 100, quantity: 5 },
  { id: '112232', cost: 100, quantity: 0 },
  { id: '112234', cost: 100, quantity: 0 },
  { id: '112235', cost: 100, quantity: 1 }
]

let numberOfItemsToBeRemoved = 0;

data.forEach((d, index) => {
  if(d.quantity === 0) {
    data.unshift(...data.splice(index, 1))
    numberOfItemsToBeRemoved++;
  }
})

console.log("deleted items: ", data.splice(0, numberOfItemsToBeRemoved))
console.log(data)

Hope this helps.

Answer 5

Just iterate over the elements of the array and check for the value of quantity and delete with splice:

let arr = [
    {
        id: "123123",
        cost: 100,
        quantity: 2,
    },
    {
        id: "112233",
        cost: 100,
        quantity: 5,
    },
    {
        id: "112233",
        cost: 100,
        quantity: 0
    },
    {
        id: "126233",
        cost: 100,
        quantity: 0
    }
];
let len = arr.length;
for( let i = 0; i < len; i++) {
    if(arr[i]['quantity'] === 0){
        arr.splice(i--,1);
        len--;
    }
}
console.log(arr);

output:

[
  { id: '123123', cost: 100, quantity: 2 },
  { id: '112233', cost: 100, quantity: 5 }
]

Answer 6

If you really have an array you can't delete -- most libraries that do this functionally will create a new object. If you want to "delete" items what you really have to do is move other elements down to over write the ones you no longer want.

So I would use the following steps.

1. Check to see if the filter item appears at all -- if it does not there is nothing to do.

2. If it does appear then then let n be the index of the first item to filter. next is the next item out after it.

   loop (index from n to index+next < size of array)
    while next is an item to filter increase next by 1
    copy from next to index
    --> increase next by 1 and back to start of loop
   

Answer 7

first get element indexes and then delete them

arr=[{
  'id': "123123",
  cost: 100,
  quantity: 2
},
{
  id: "112233",
  cost: 100,
  quantity: 5
},
{
  id: "112233",
  cost: 100,
  quantity: 0
},
{
  id: "126233",
  cost: 100,
  quantity: 0
}
]
index=[]
arr.forEach(x => {
 if (x.quantity==0) index.push(arr.indexOf(x))
});

    i=0
index.forEach(x=>{
  arr.splice(x+i,1)
  i--
})
console.log(arr)