filter with callback javascript code example

Example 1: javascript object filter

function objectFilter = (obj, predicate) => 
    Object.keys(obj)
          .filter( key => predicate(obj[key]) )
          .reduce( (res, key) => (res[key] = obj[key], res), {} );

// Example use:
var scores = {
    John: 2, Sarah: 3, Janet: 1
};

var filtered = objectFilter(scores, num => num > 1); 
console.log(filtered);

Example 2: filter

const array = [-3, -2, -1, 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13]; 

function isPrime(num) {
  for (let i = 2; num > i; i++) {
    if (num % i == 0) {
      return false;
    }
  }
  return num > 1;
}

console.log(array.filter(isPrime)); // [2, 3, 5, 7, 11, 13]

Example 3: javascript array filter

run.addEventListener("click", function () {
    let array = [];
    people.forEach((elem) => {
      // elem before age to target
      if (elem.age > 18) {
        array.push(elem); // each array elem > 18 is "pushed" inside the new array
        // console.log(array); nope : messes things up
      } else {
        (""); // no need to declare this through console.log
      }
    });
    console.log(array); //and there you have it : filtered array
  });