CODEWITHSUNDEEP
javascriptlodash
alex
alex

Reputation: 7601

Why is _.difference returning all the items?

I have two lists, oldPanodatas and newPanodatas. I want to get only the objects in newPanodatas that aren't present in oldPanodatas. I did this:

var filteredPanodatas = _.difference(newPanodatas, oldPanodatas)

But I'm getting all the items, _.difference is not filtering anything whatsoever:

OLD: Object {roomModelId: "56a9e0088ac247005538d6d3", x: 262, index: 1, y: 211, panoDataRotate: 0…}
OLD: Object {roomModelId: "56a9e0088ac247005538d6d3", x: 177, index: 0, y: 182, panoDataRotate: 0…}
NEW: Object {index: 0, x: 177, y: 182, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}
NEW: Object {index: 1, x: 262, y: 211, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}
NEW: Object {index: 2, x: 200, y: 200, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}
FILTERED: Object {index: 0, x: 177, y: 182, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}
FILTERED: Object {index: 1, x: 262, y: 211, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}
FILTERED: Object {index: 2, x: 200, y: 200, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}

Why is this? What's the correct way to accomplish what I want?

Upvotes: 0

Views: 41

Answers (1)

zangw
zangw

Reputation: 48406

Try it with differceWith, the isEqual comparator which is invoked to compare elements of array to values

_.differenceWith(newPanodatas, oldPanodatas, _.isEqual);

Code sample,

var old = [{roomModelId: "56a9e0088ac247005538d6d3", x: 262, index: 1, y: 211, panoDataRotate: 0},  {roomModelId: "56a9e0088ac247005538d6d3", x: 177, index: 0, y: 182, panoDataRotate: 0}];
newobj = [{index: 0, x: 177, y: 182, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}, {index: 1, x: 262, y: 211, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}, {index: 2, x: 200, y: 200, roomModelId: "56a9e0088ac247005538d6d3", panoDataRotate: 0}];
r = _.differenceWith(newobj, old, _.isEqual);

The result of r

[{index: 2, panoDataRotate: 0, roomModelId: "56a9e0088ac247005538d6d3", x: 200, y: 200}]

Upvotes: 1

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