How can I remove an element from a list, with lodash?

Question

I have an object that looks like this:

var obj = {
    "objectiveDetailId": 285,
    "objectiveId": 29,
    "number": 1,
    "text": "x",
    "subTopics": [{
        "subTopicId": 1,
        "number": 1
    }, {
        "subTopicId": 2,
        "number": 32
    }, {
        "subTopicId": 3,
        "number": 22
    }]
}
var stToDelete = 2;

I have lodash installed in my application for other things. Is there an efficient way to use lodash to delete the entry: {"subTopicId":2, "number":32} from the obj object?

Or is there a javascript way to do this?

Answer 1

As lyyons pointed out in the comments, more idiomatic and lodashy way to do this would be to use _.remove, like this

_.remove(obj.subTopics, {
    subTopicId: stToDelete
});

Apart from that, you can pass a predicate function whose result will be used to determine if the current element has to be removed or not.

_.remove(obj.subTopics, function(currentObject) {
    return currentObject.subTopicId === stToDelete;
});

---

Alternatively, you can create a new array by filtering the old one with _.filter and assign it to the same object, like this

obj.subTopics = _.filter(obj.subTopics, function(currentObject) {
    return currentObject.subTopicId === stToDelete;
});

Or

obj.subTopics = _.filter(obj.subTopics, {subTopicId: stToDelete});

Answer 2

Just use vanilla JS. You can use splice to remove the element:

obj.subTopics.splice(1, 1);

Demo

Answer 3

you can do it with _pull.

_.pull(obj["subTopics"] , {"subTopicId":2, "number":32});

check the reference

Answer 4

You can now use _.reject which allows you to filter based on what you need to get rid of, instead of what you need to keep.

unlike _.pull or _.remove that only work on arrays, ._reject is working on any Collection

obj.subTopics = _.reject(obj.subTopics, (o) => {
  return o.number >= 32;
});

Answer 5

In Addition to @thefourtheye answer, using predicate instead of traditional anonymous functions:

  _.remove(obj.subTopics, (currentObject) => {
        return currentObject.subTopicId === stToDelete;
    });

OR

obj.subTopics = _.filter(obj.subTopics, (currentObject) => {
    return currentObject.subTopicId === stToDelete;
});

Answer 6

lodash and typescript

const clearSubTopics = _.filter(obj.subTopics, topic => (!_.isEqual(topic.subTopicId, 2)));
console.log(clearSubTopics);

Answer 7

Here is the simple lodash function with array and deleting it with the index number.

index_tobe_delete = 1

fruit = [{a: "apple"}, {b: "banana"}, {c: "choco"}]
_.filter(fruit, (value, key)=> {
return (key !== index_tobe_delete)
})