JavaScript provides the very useful Array.filter() method for extracting elements from an array that match an input condition, and this behavior can be replicated using the Array.forEach() method as well:

function filter(arr, callback) {
  const result = []
  arr.forEach(element => {
     if (callback(element)) {
      result.push(element)
    }
  })
  return result
}

Where the arr argument is the array, and the callback argument represents the conditional expression to be evaluated for each item:

filter([1, 2, 3], num => num >= 0) // [1, 2, 3]

filter([1, 2, 3], num => num > 5) // []

#TIL #TheMoreYouKnow