如何遍历对象数组并使用 Lodash 查找出现次数和元素名称

Question

Related to my other question, where the image is How do I get rid of PROTOTYPE in my new JSON Object from an Array?

I want to be able to do the following:

Taking this one step further...

Each of those MARKET (name, displayName) which are both the same for now, have from 1 to "n" number of items within them.

So, I want to COUNT how many ITEMS are within or repeated.

For example:

NAME: "IL" may have 300 
NAME: "WA" may have 1000 
NAME: "OR" may have 100 

and so on.

Inside these objects, the word MARKET is there. Market is what's above: IL, WA, CA, and so on are MARKETS like so:

[
    {
      ID: 1,
      NAME: "SomeName1",
      MARKET: "IL",
      LOCATION: "6 Miles east"
    },
    {
      ID: 2,
      NAME: "SomeName2",
      MARKET: "IL",
      LOCATION: "36 Miles east"
    },
    {
      ID: 3,
      NAME: "SomeName3",
      MARKET: "WA",
      LOCATION: "3 Miles west"
    },
    {
      ID: 4,
      NAME: "SomeName4",
      MARKET: "WA",
      LOCATION: "33 Miles west"
    },
    {
      ID: 5,
      NAME: "SomeName5",
      MARKET: "OR",
      LOCATION: "23 Miles north"
    },
    ...
]

I want to add a count to the MAP function I received as a solution:

const newObj = newMarketArray.map(e => ({ name: e, displayName: e }));

So that when the values appear as in the image above, I can get the number of occurrences of, WA, IL and OR for example.

The final JSON should have an additional element:

   displayName: WA,
   name: WA,
   count: 33

And finally, I want to SORT the values of the JSON object which is probably very easy.

UPDATE: A question was raised that the MAP

const newObj = newMarketArray.map(e => ({ name: e, displayName: e })); 

is false. That's not true. It returns the values in the IMAGE. So that is most certainly not false.

All I need is to COUNT the number of instances say, CA appears and place it like so:

const newObj = newMarketArray.map(e => ({ name: e, displayName: e, count: somecount }));

FYI: newMarketArray contains 3300+ objects

Answer 1

If i have well understood what you want:

 newMarketArray = [ { ID: 1, NAME: "SomeName1", MARKET: "IL", LOCATION: "6 Miles east" }, { ID: 2, NAME: "SomeName2", MARKET: "IL", LOCATION: "36 Miles east" }, { ID: 3, NAME: "SomeName3", MARKET: "WA", LOCATION: "3 Miles west" }, { ID: 4, NAME: "SomeName4", MARKET: "WA", LOCATION: "33 Miles west" }, { ID: 5, NAME: "SomeName5", MARKET: "OR", LOCATION: "23 Miles north" } ] let objCount = newMarketArray.reduce((acc, obj) => { acc[obj.MARKET] = (acc[obj.MARKET] || 0) + 1; return acc; }, {}); console.log(objCount); const newObj = newMarketArray.map(e => ({ name: e, displayName: e, COUNT: objCount[e.MARKET]})); console.log(newObj)

After that, you could sort as you want the dictionary (by the value you want..)