Feature request: _.deleteWhere

[morgoth]

Currently having array of objects, to delete one of them I need to write:

var collection = [{id: 1}, {id: 3}];
var objectToRemove = _.findWhere(collection, function (obj) { return obj.id === 3 });
var objectIndex = collection.indexOf(objectToRemove);
collection.splice(objectIndex, 1);

It would be nice to have in underscore something like:

_.deleteWhere(collection, {id: 2})

If you find this useful I can try to implement it and send a PR.

[akre54]

One of Underscore's philosophies is to expose reusable, composable methods so you can implement these types of special functions yourself, keeping the library small and purposefully managed. It should be fairly easy to do in your own copy with mixin.

_.mixin({
  deleteWhere: function(collection, predicate) {
    var obj = _.findWhere(collection, predicate);
    collection.splice(_.indexOf(collection, obj), 1);
  }
});

_.deleteWhere(collection, {id: 2});

[jdalton]

@akre54 It gets a bit trickier when you want to remove all matches and isn't something devs can compose easily.

@morgoth You can find this method in Lo-Dash as _.remove, (_.remove(array, {id: 2}), or as an individual method npm package. I'm sure there's others on npm too.

If you go the _.mixin route, implementing it on your own, you can leverage Underscore's new _.iteratee method to support callbacks as well as "_.pluck" & "_where" callback shorthands.

@joshuacc Have y'all considered array/object mutator methods for underscore-contrib? It's one of those things that seems to come up from time to time.

Related to #1848.

[joshuacc]

@jdalton Not so far, but it sounds reasonable to me. This example in particular seems quite useful. I'll create an issue to track it.

[jashkenas]

I think this would be a nice function to add to Underscore...

[akre54]

Usefulness or niceness aside, it fits closer to a mixin or
underscore.contrib than a core underscore method.

[megawac]

It's not a functional method but other libs like Mootools have this as well

I'd 👍 this addition

[akre54]

The problem is, ideally we'd also include a more generic .delete that
takes an array and a reference to an object, but that's not much more than
sugar over arr.splice(.indexOf(arr, obj), 1)). It could be composed with
findWhere, but I'm not sure the extra abstraction (and the addition to the
Underscore API) is worth it.

On Fri, Sep 19, 2014 at 4:52 PM, Graeme Yeates notifications@github.com
wrote:

It's not a functional method but other libs like Mootools
http://mootools.net/docs/core/Types/Array#Array:erase have this as well

I'd [image: 👍] this addition

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#1856 (comment)
.

[jdalton]

I think of it more like a friend of _.reject, because it removes any element the predicate returns truthy for, but it mutates the array.

[megawac]

It's not the most trivial thing to implement if you want to remove all matches cause of splice. Quick port based on MooTools docs

_.deleteWhere = function(list, what) {
     var predicate = _.iteratee(what), index = this.length;
     while(index--) {
           if (predicate(list[index], index, list) this.splice(index,1);
     }
     return list;
}