freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-data-structures/check-if-an-object-has-a-property/index.md

title

title
Check if an Object has a Property

Check if an Object has a Property

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Solutions

Solution 1 (Click to Show/Hide)

let users = {
  Alan: {
    age: 27,
    online: true
  },
  Jeff: {
    age: 32,
    online: true
  },
  Sarah: {
    age: 48,
    online: true
  },
  Ryan: {
    age: 19,
    online: true
  }
};

function isEveryoneHere(obj) {
  if (
    obj.hasOwnProperty("Alan") &&
    obj.hasOwnProperty("Jeff") &&
    obj.hasOwnProperty("Sarah") &&
    obj.hasOwnProperty("Ryan")
  ) {
    return true;
  }
  return false;
}

Code Explanation

• Checks whether object contains all users by using the hasOwnProperty method for each name with the && operator to return a true or false value.

Solution 2 (Click to Show/Hide)

let users = {
  Alan: {
    age: 27,
    online: true
  },
  Jeff: {
    age: 32,
    online: true
  },
  Sarah: {
    age: 48,
    online: true
  },
  Ryan: {
    age: 19,
    online: true
  }
};

function isEveryoneHere(obj) {
  return ["Alan", "Jeff", "Sarah", "Ryan"].every(name =>
    obj.hasOwnProperty(name)
  );
}

Code Explanation

• Uses an array with all of the names which should be present in the object.
• The every method is used to validate all of names used in conjunction with the hasOwnProperty method result in a value of true being returned during each iteration.
• If at least one name is not found using the hasOwnProperty method, the every method returns false.

Relevant Links

• Array.prototype.every