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

问题

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?

回答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;
});

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

回答2:

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

obj.subTopics.splice(1, 1);

Demo

回答3:

you can do it with _pull.

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

check the reference

回答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;
});

回答5:

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

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

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

回答6:

lodash and typescript

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

回答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)
})

回答8:

There are four ways to do this as I know

const array = [{id:1,name:'Jim'},{id:2,name:'Parker'}];
const toDelete = 1;

The first:

_.reject(array, {id:toDelete})

The second one is :

_.remove(array, {id:toDelete})

In this way the array will be mutated.

The third one is :

_.differenceBy(array,[{id:toDelete}],'id')
// If you can get remove item 
// _.differenceWith(array,[removeItem])

The last one is:

_.filter(array,({id})=>id!==toDelete)

I am learning lodash

Answer to make a record, so that I can find it later.

来源：https://stackoverflow.com/questions/21281286/how-can-i-remove-an-element-from-a-list-with-lodash

标签

javascript

arrays

object

lodash