feature: 'screen' filter object creating a new object about lodash HOT 10 CLOSED

_.pick and _.drop are object filter methods, currently accepting property names to include/exclude. I bet we could extend those to use a callback similar to how _.countBy, _.groupBy, and _.sortBy allow a callback or a property name.

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Overloading _.pick and _.drop seems like a great plan.

_.screen({a:1,b:2,c:3},function(item){return item!==2})
// {a=1, c=3}

_.pick({a:1,b:2,c:3},["a","c"])
// {a=1,c=3}

As a side note, any idea why _.each doesn't return an object with callback results.

function fn(list,fn){
    var o = new list.constructor();
    _.each(list,function(i,k,l){
        o[k] = fn(i);
    });
    return o;
}
fn({a:1,b:2,c:3},function(i,k,l){return i*=2;});
// {a=2,b=4,c=6}

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@shanimal

As a side note, any idea why _.each doesn't return an object with callback results.

_.each returns the collection passed to it.

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@shanimal Regarding _.each: you're actually looking for _.map.

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Hi @kitcambridge

Actually _.map returns an array. I want an object with the keys preserved.

function fn(list,fn){
    var o = new list.constructor();
    _.each(list,function(i,k,l){
        o[k] = fn(i);
    });
    return o;
}
var o = {a:1,b:2,c:3};
fn(o,_.identity); // {a=1,b=2,c=3}
_.map(o,_.identity); // [1,2,3]

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@shanimal I patched _.pick and _.drop, you should be good to go.

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@jdalton That's awesome! Thanks.

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@shanimal Whoops, I completely missed what you were trying to do. _.map definitely won't work, then. Apologies.

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np @kitcambridge thanks for the feedback.

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