Removing Object From One Array If Present In Another Array Based On Value

Last question did not get well received as was a possible duplicate. Writing again to explain how this is slightly different as can't get the solution I want. I have an array calle

Solution 1:

It looks like a simple filter to me:

let filteredUsers = _USERS.filter(u => !newArray.includes(u.useruid))

Here it is in action:

var newArray = ["BLRlXKIeWkanHiSCXbBCFRTIaqk1", "sF4gWbZvAMPmrbeHsKzln7LowOx2"]

var _USERS = [{ gender: "male", name: "Rich", username: "rich@rich.com", useruid: "BLRlXKIeWkanHiSCXbBCFRTIaqk1" }]

let filteredUsers = _USERS.filter(u => !newArray.includes(u.useruid));

/*Printing*//*Before*/document.write("Before: <br>" + JSON.stringify(_USERS) + "<br><br>");
/*After*/document.write("After <br>" + JSON.stringify(filteredUsers));

Solution 2:

Here's a simple solution if I understand your question:

_USERS = _USERS.filter(u => newArray.indexOf(u.useruid)===-1);

Solution 3:

There are several clean ways to do this, but just to comment on your splice implementation. Splice expects the first parameter to be an index of an element not an object, so if you call splice(1) then it will delete from the object at index 1 to the end of the array. The second parameter is the number of elements that should be deleted, so splice(1, 1) will delete only the element at index 1. Here is some sample code that may help:

var newArray = ["xyz", "def"];

var _USERS = [
{useruid: "abc"},
{useruid: "def"},
{useruid: "ghi"}
];

for(var i = 0; i < _USERS.length; i++)
{
    for(var j = 0; j < newArray.length; j++)
  {
    if(_USERS[i].useruid == newArray[j])
    {
      _USERS.splice(i, 1); //remove element at index i
      i--; //decrement i because we now removed an elementbreak; //move to next element
    }
  }
}

JSFiddle For Reference

Solution 4:

To mutate your original array with a loop and Array#splice you need to run your loop in reverse as the length of the array and indexes of items in your array will change when you remove an item, and hence you will miss some of the items. Examples in ES6.

With a forward running loop, incorrect result.

functioncustomRemove(users, unwanted) {
  for (let user of users.entries()) {
    if (unwanted.includes(user[1].useruid)) {
      users.splice(user[0], 1);
    }
  }
}

const newArray = ['BLRlXKIeWkanHiSCXbBCFRTIaqk1', 'sF4gWbZvAMPmrbeHsKzln7LowOx2'];
const _USERS = [{
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk1'
}, {
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk1'
}, {
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk2'
}, {
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk1'
}];

console.log(JSON.stringify(_USERS));
customRemove(_USERS, newArray);
console.log(JSON.stringify(_USERS));

With a reverse running loop, correct result.

// Generator creates index number in reversefunction* reverseIndexes(arr) {
  let key = arr.length - 1;
  while (key >= 0) {
    yield key;
    key -= 1;
  }
}

// Generator like Array#entries but in reversefunction* reverseEntries(arr) {
  for (let key ofreverseIndexes(arr)) {
    yield [key, arr[key]];
  }
}

functioncustomRemove(users, unwanted) {
  // Reversed loop removing unwanted matches with Array#splicefor (let user ofreverseEntries(users)) {
    if (unwanted.includes(user[1].useruid)) {
      users.splice(user[0], 1);
    }
  }
}

const newArray = ['BLRlXKIeWkanHiSCXbBCFRTIaqk1', 'sF4gWbZvAMPmrbeHsKzln7LowOx2'];
const _USERS = [{
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk1'
}, {
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk1'
}, {
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk2'
}, {
  useruid: 'BLRlXKIeWkanHiSCXbBCFRTIaqk1'
}];

console.log(JSON.stringify(_USERS));
customRemove(_USERS, newArray);
console.log(JSON.stringify(_USERS));

Solution 5:

Well just to expand on @Denys answer. I have taken the .filter approach and added it to a jsfiddle. I've only included useruid for a user but that should be enough to filter as required.