Find Object with Property in Array

Javascript find object with matching property in array of objects and get another property if exists

The smallest method is not necessarily the most efficient. I would do it this way:

let wantedProperty = (arrayOfObjects.find(obj => obj.id === wantedObject.id) || {}).title || 'None Found';

How to determine if Javascript array contains an object with an attribute that equals a given value?

2018 edit: This answer is from 2011, before browsers had widely supported array filtering methods and arrow functions. Have a look at CAFxX's answer.

There is no "magic" way to check for something in an array without a loop. Even if you use some function, the function itself will use a loop. What you can do is break out of the loop as soon as you find what you're looking for to minimize computational time.

var found = false;
for(var i = 0; i < vendors.length; i++) {
    if (vendors[i].Name == 'Magenic') {
        found = true;
        break;
    }
}

Find object by id in an array of JavaScript objects

Use the find() method:

myArray.find(x => x.id === '45').foo;

From MDN:

The find() method returns the first value in the array, if an element in the array satisfies the provided testing function. Otherwise undefined is returned.

If you want to find its index instead, use findIndex():

myArray.findIndex(x => x.id === '45');

From MDN:

The findIndex() method returns the index of the first element in the array that satisfies the provided testing function. Otherwise -1 is returned.

If you want to get an array of matching elements, use the filter() method instead:

myArray.filter(x => x.id === '45');

This will return an array of objects. If you want to get an array of foo properties, you can do this with the map() method:

myArray.filter(x => x.id === '45').map(x => x.foo);

Side note: methods like find() or filter(), and arrow functions are not supported by older browsers (like IE), so if you want to support these browsers, you should transpile your code using Babel (with the polyfill).

search for a specific property in array of objects and return boolean

You can use some. So basically it will return a boolean value if any of the object property in array matches the required value

let arr = [{
    name: "john",
    age: 22
  },
  {
    name: "george",
    age: 55
  }
];
let obj = {
  name: "bill",
  age: 55
}

const val = arr.some(item => item.age === obj.age);
console.log(val)

How to check if property of an objects of array matches with one of the values in another array of object

First off, you'll have to make sure if the ID types are correct. Users has Number type for IDs but attendingUsers has String type.

Let's say they're both the same type for the code below (I'm going with string).

You can turn the attendingUsers array into an array of strings with:

const attendingUsersIds = attendingUsers.map(attendingUser => attendingUser.id)

Then match the ids with:

const matchedUsers = users.filter(user => attendingUsersIds.includes(user.id))

If they're intended to not be the same type, you can use user.id.toString() to turn the Number into a String or parseInt(attendingUser.id) to turn the String into a Number.

Finding objects in array by multiple (and unknown in advance) properties

You can use filter to filter out the array.

const items = [
  {
    firstName: "John",
    lastName: "Doe",
    password: "*******",
    email: "john@i.com",
    role: "ROLE_ADMIN"
  },
  {
    firstName: "Jane",
    lastName: "Doe",
    password: "********",
    email: "jane@i.com",
    role: "ROLE_USER"
  },
  {
    firstName: "John",
    lastName: "Roe",
    password: "**********",
    email: "johnr@i.com",
    role: "ROLE_USER"
  }
];

function match(params) {
  const keys = Object.keys(params);
  return items.filter((item) => {
    let flag = true;
    keys.every((key) => {
      if ((item[key] && item[key] !== params[key]) || !item[key]) {
        flag = false;
        return false;
      }
      return true;
    });
    return flag;
  });
}

console.log(match({ firstName: "John",role: "ROLE_USER" }));