How to compare two array of object and get common objects

Question

Hello guys I have two arrays

var elements = [{
        \"id\": \"id_1\",
        \"type\": \"input\",
        \"businesstype\": { \"type\": \"text\" }
    },         


        

Answer 1

You could filter it with a recursive approach for the nested objects.

const isObject = o => o && typeof o === 'object',
      isEqual = (f, o) =>
          isObject(o) && Object.keys(f).every(k =>
              isObject(f[k]) && isEqual(f[k], o[k]) || o[k] === f[k]
          );

var elements = [{ id: "id_1", type: "input", businesstype: { type: "text" } }, { type: "label", id: "id_234" }, { id: "id_16677", type: "div" }, { id: "id_155", type: "input", businesstype: { type: "password" } }],
    filterArray = [{ type: 'input', businesstype: { type: 'text' } }, { type: 'div' }],
    result = elements.filter(o => filterArray.some(f => isEqual(f, o)));

console.log(result);

.as-console-wrapper { max-height: 100% !important; top: 0; }

Answer 2

If your filterArray does not have further objects in its hierarchy, you can make do with this solution - see demo below:

var elements=[{id:"id_1",type:"input",businesstype:{type:"text"}},{type:"label",id:"id_234"},{id:"id_16677",type:"div"},{id:"id_155",type:"input",businesstype:{type:"password"}}],filterArray=[{type:"input",businesstype:{type:"text"}},{type:"div"}];

var result = elements.filter(function(e) {
  return filterArray.some(function(f) {
    return Object.keys(f).every(function(k) {
      return e.hasOwnProperty(k) && Object.keys(f[k]).every(function(n) {
        return e[k][n] == f[k][n];
      });
    });
  });
});

console.log(result);

.as-console-wrapper {top: 0;max-height: 100%!important;}

Answer 3

(Since you tagged Ramda)

Ramda already has many useful (object) comparison functions you can use to make the filter a bit easier to read. (i.e.: equals and other functions that use it under the hood, like contains)

You could, for example, write:

const elements=[{id:"id_1",type:"input",businesstype:{type:"text"}},{type:"label",id:"id_234"},{id:"id_16677",type:"div"},{id:"id_155",type:"input",businesstype:{type:"password"}}];
const filterArray=[{type:'input',businesstype:{type:'text'}},{type:'div'}];

// Describes how to define "equality"
// i.e.: elements are equal if type and businesstype match
// e.g.: pick(["a", "b"], { a: 1, b: 2, c: 3}) -> { a: 1, b: 2}
const comparisonObjectFor = pick(["type", "businesstype"]);

// Compares an object's comparison representation to another object
const elEquals = compose(whereEq, comparisonObjectFor);

// Creates a filter method that searches an array
const inFilterArray = matchElements => el => any(elEquals(el), matchElements);

// Run the code on our data
filter(inFilterArray(filterArray), elements);

Running example here

I don't think this is necessarily the best solution (in terms of reusability, readability), but I'd advice you to not inline deep object/array comparison methods since:

1. You're probably going to use them more than once
2. They are hard to understand/predict if not given the right name & documentation
3. They are prone to (small) bugs because of their complexity

In other words: since you've tagged lodash and Ramda, I can safely advice to use a well tested, well used library for the comparison of your objects.