查找对象数组的所有常见元素-Javascript

Question

I have data structured as follows:

var Items = [{"Name":"type1","Options":[1,2,5]},{"Name":"type2","Options":[1,2]},{"Name":"type1","Options":[2,5]}];

I am fairly new to javascript but I'm trying to figure out the common options associated with each name type.

The number of elements in the Items array is arbitrary. So I could have 40 for example.

My expected output for the above data would be

CommonOptions = [{"Name":"type1","Options":[2,5]},{"Name":"type2","Options":[1,2]}];

because 2 and 5 are common to all elements with name type1 and 1,2 are common to all elements with elements with name type2. I don't know how to access the data correctly.

Here is where I am up to. If someone could steer me in the right direction I'd really appreciate it.

 var Items = [{ "Name": "type1", "Options": [1, 2, 5] }, { "Name": "type2", "Options": [1, 2] }, { "Name": "type1", "Options": [2, 5] }]; //Define the Common Options Array as the first options and associated name var CommonOptions = []; CommonOptions.push(Items[0]); //the first item is already in the common options array so start at 1 for (var i = 1, iLen = Items.length - 1; i < iLen; i++) { for (var j = 0, cLen = CommonOptions.length; j < cLen; j++) { //add all unique by name options to common options array if (CommonOptions[j].Name.indexOf(Items[i].Name) === -1) { //item name is not in the common options array //add item to common options array CommonOptions.push(Items[i]); } else { //item name is in the common options array // if it is in the common options array then check each Option in the Option array against the common options of that name //CommonOptions[j].Options.indexOf(Items[i].Options)===-1 } } } console.log(CommonOptions); 

Answer 1

You could use a hash table for same named objects and filter Options for common elements.

 var items = [{ Name: "type1", Options: [1, 2, 5] }, { Name: "type2", Options: [1, 2] }, { Name: "type1", Options: [2, 5] }], hash = Object.create(null), common = items.reduce(function (r, o) { if (hash[o.Name]) { hash[o.Name].Options = hash[o.Name].Options.filter(function (v) { return o.Options.indexOf(v) !== -1; }); } else { hash[o.Name] = { Name: o.Name, Options: o.Options.slice() }; r.push(hash[o.Name]); } return r; }, []); console.log(common); 

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Answer 2

You just need to keep separate the current state of the array for each name, and further filter it as that name is encountered.

 const Items = [{"Name":"type1","Options":[1,2,5]},{"Name":"type2","Options":[1,2]},{"Name":"type1","Options":[2,5]}]; const m = Items.reduce((m, o) => { const a = m.get(o.Name); return m.set(o.Name, a ? a.filter(n => o.Options.includes(n)) : o.Options); }, new Map()); const res = Array.from(m.entries(), ([Name, Options]) => ({Name, Options})); console.log(res);