How to check and return true if json object key is having all same values in javascript?

Question

I have the following sample JSON object:

var data = [ {
  "id" : 1,
  "name" : "Abc",
  "age" : 30,
  "married" : true,
  "city": "ABC"
}, {
  "id" : 2,
  "name" : "Def",
  "age" : 25,
  "married" : true,
  "city": "ABC"
}, {
  "id" : 3,
  "name" : "Pqr",
  "age" : 28,
  "married" : false,
  "city": "ABC"
}, {
  "id" : 4,
  "name" : "Xyz",
  "age" : 40,
  "married" : true,
  "city": "ABC"
} ];

I want to return true and store it in a variable if all city key values are ABC only, or else it should return false(i.e if one of city key values is not ABC) from the given JSON object. Can anyone please let me know on how to achieve this. Thanks in advance.

Answer 1

Using Array#every:

const data = [ { "id" : 1, "name" : "Abc", "age" : 30, "married" : true, "city": "ABC" }, { "id" : 2, "name" : "Def", "age" : 25, "married" : true, "city": "ABC" }, { "id" : 3, "name" : "Pqr", "age" : 28, "married" : false, "city": "ABC" }, { "id" : 4, "name" : "Xyz", "age" : 40, "married" : true, "city": "ABC" } ];

const valid = data.every(({ city }) => city === 'ABC');

console.log(valid);