Checking existence of all continents in array of objects in JavaScript

Problem

We are required to write a JavaScript function that takes in an array of objects that contains data about the continent of belonging for some people.

Our function should return true if it finds six different continents in the array of objects, false otherwise.

Example

Following is the code −

const people = [
               { firstName: 'Dinesh', lastName: 'A.', country: 'Algeria', continent: 'Africa', age: 25, language: 'JavaScript' },
               { firstName: 'Ishan', lastName: 'M.', country: 'Chile', continent: 'South America', age: 37, language: 'C' },
               { firstName: 'Rohit', lastName: 'X.', country: 'China', continent: 'Asia', age: 39, language: 'Ruby' },
               { firstName: 'Manpreet', lastName: 'P.', country: 'Andorra', continent: 'Europe', age: 55, language: 'Ruby' },
               { firstName: 'Rahul', lastName: 'Q.', country: 'Australia', continent: 'Australia', age: 65, language: 'PHP' },
               ];
const checkAllContinent = (arr = []) => {
   const all = ['Africa', 'South America', 'North America', 'Europe', 'Asia', 'Australia'];
   const listed = arr.map(obj => {
      return obj.continent;
   });
   for(let i = 0; i < listed.length; i++){
      const cont = listed[i];
      const ind = all.indexOf(cont);
      if(ind !== -1){
         all.splice(ind, 1);
      };
   };
   return all.length === 0;
};
console.log(checkAllContinent(people));

Output

false