Find object in array of objects where all key-value pairs are unique

Question

Say I have an array of objects {key:string} where all the keys-value pairs are unique (keys or values are allowed to the same in different objects, but the same key value pair)

const arr = [{a_1:"val_1"}, {a_2:"val_2"}, ..., {a_n:"val_n"}];

and I have a target object

const target = {a_i: "val_i"};

I want to find if target exists in arr ie if it's key and value match a certain object in arr . If true, then I want the object from arr to be returned.

example: (Edited)

const target = {foo: "bar"};
const arr = [{foo: "bar"}, {corona: "COVID-19"}, {foo: "notBar"}, {notFoo: "bar"}];

In this example, the search of target on arr will return {foo:"bar"} from arr .

Note:

arr.find(ob => ob === target);

returns undefined.

Answer 1

Those 2 have different references. Maybe with JSON.stringify() it can work.

 const target = {foo: "bar"}; const arr = [{foo: "bar"}, {corona: "COVID-19"}]; const result = arr.find(ob => JSON.stringify(ob) === JSON.stringify(target)); console.log(result);

Or a better option to use .every() as the following:

 const target = {foo: "bar"}; const arr = [{foo: "bar"}, {corona: "COVID-19"}]; const keysT = Object.keys(target); const result = arr.find(e => { const keysE = Object.keys(e); return keysE.length === keysT.length && keysE.every(k => e[k] === target[k]) }); console.log(result);

I hope this helps!

Answer 2

that will do it if keys are not in order. But not if the key values of the target object objects itself.

const target = {foo: "bar"};
const arr = [{foo: "bar"}, {corona: "COVID-19"}];

arr.find(ob => {
  for (key in target) {
    if (!(key in ob)) return false;
    if (ob[key] !== target[key]) return false;
  }
  return true;
});

Edit:
With "keys are not in order", I mean:

const target = {foo: "bar", bar: "foo"};
const arr = [{bar: "foo", foo: "bar"}, {corona: "COVID-19", foo: "bar"}];

Answer 3

If there's a single key/value pair in your target option, you may use Array.prototype.some() to look up through your source array (until match is found) and extract target key/value, using Object.entries() , like that:

 const arr = [{a_1:"val_1"}, {a_2:"val_2"}, {a_n:"val_n"}], target = {a_2: "val_2"}, [[targetKey, targetValue]] = Object.entries(target), hasMatch = arr.some(item => targetKey in item && item[targetKey] == targetValue) console.log(hasMatch)

 .as-console-wrapper{min-height:100%;}