Remove items from array using id with Javascript

Question

I have a function like this: pickListSelect array is has all id (numbers) to delete objects in source array, and target array it is to push elements deleted from source array.

    function copy(pickListSelect, source, target) {

         var i, id;

         for (i = 0; i < pickListSelect.length; i++) {
              id = pickListSelect[i];              
              source.splice(id,1);
         }
         pickListSelect = [];
   }

So what I need is delete specific object from source array. I tried with that code but for example if I need to delete object with id=5, it only deleted item 5 from the list.

The structure of source array is this:

    [Object, Object, Object, Object, Object, Object, Object, Object, Object]
    0:Object
    plantId:1
    plantName:"Plant 1"

...the rest of others are similar object

t1m0n · Accepted Answer · 2016-04-26 17:49:01Z

You need to find plant in your source by plantId first, and then delete it from original array and push to target. Open console and it should log deleted plants:

var plants = [
    {
        plantId: 1,
        plantName: 'plant 1'
    },
    {
        plantId: 2,
        plantName: 'plant 2'
    },
    {
        plantId: 3,
        plantName: 'plant 3'
    },
    {
        plantId: 4,
        plantName: 'plant 4'
    }
];

function copy(pickListSelect, source, target) {
    var i, id, el;

    for (i = 0; i < pickListSelect.length; i++) {
        id = pickListSelect[i];
        el = findPlant(source, id);
        source.splice(source.indexOf(el), 1);
        target.push(el);
    }
}

function findPlant (arr, id) {
    return arr.filter(function (plant) {
        return plant.plantId == id
    })[0]
}

var test = [];

copy([2,3], plants, test);

console.log(test);

omarjmh · Accepted Answer · 2016-04-26 17:42:33Z

2

When you use .splice you need to pass in the start index at which to splice and the amount of items to splice, try this:

source.splice(i,1); // i is your starting index here


array.splice(start, deleteCount[, item1[, item2[, ...]]])

MDN on .splice

Now in your actual code you need to check to see if the id matches and then splice using the above code:

function copy(pickListSelect, source, target) {

     var i, id;

     for (i = 0; i < pickListSelect.length; i++) {
          if (pickListSelect[i].id === someId) {              
            source.splice(i,1);
          }
     }
     pickListSelect = [];
 }

edited Apr 26, 2016 at 17:42

answered Apr 26, 2016 at 17:39

omarjmh

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3 Comments

omarjmh Over a year ago

see edit...you need to check to see if the ids are the same too

Angel Cuenca Over a year ago

"pickListSelect" array only contains of all id to delete. But on "source" is an array of objects, which each object contains id and plant name properties.

Angel Cuenca Over a year ago

pickListSelect[i].id it is not possible. The structure array is [1, 2] only id

Pratik Bhattacharya · Accepted Answer · 2016-04-26 17:56:19Z

1

You can take a look at this fiddler here. I have used underscore.js to find the correct element from source and move it to the target array.

var copy = function(pickListSelect, source, target) {
    for (i = 0; i < pickListSelect.length; i++) {
      id = pickListSelect[i];
      var deleteIndex = _.findIndex(source, {Id: id});
            var deletedItem = source.splice(deleteIndex, 1);
            target.push(deletedItem[0])
    }
        pickListSelect = [];
    return target;
  }

answered Apr 26, 2016 at 17:56

Pratik Bhattacharya

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Comments

James Buck · Accepted Answer · 2016-04-26 17:58:58Z

1

You're not looking up the index of the source array with a matching id. It might be better to do something like this.

var idsToRemove = {};

// build an object of ids to remove (effectively a hashset)
for (var i = 0; i < pickSelectList.length; i++) {
    idsToRemove[pickSelectList[i]] = true;
}

// loop through the source array to find any objects with ids to remove
for (var j = 0; j < source.length; j++) {
    if (source[j].plantId in idsToRemove) {
        target.push(source.splice(j, 1));
    }
}

edited Apr 26, 2016 at 17:58

answered Apr 26, 2016 at 17:49

James Buck

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