takeUntil.js

const eqArrays = function(arr1, arr2) {
  if (arr1.length !== arr2.length) {
    return false;
  }
  for (let i = 0; i < arr1.length; i++) {
    if (arr1[i] !== arr2[i]) {
      return false;
    }
  }
  return true;
};

const assertArraysEqual = function(arr1, arr2) {
  if (eqArrays(arr1, arr2)) {
    console.log(`✅✅✅ Assertion Passed: ${arr1} === ${arr2}`);
  } else {
    console.log(`🛑🛑🛑 Assertion Failed: ${arr1} !== ${arr2}`);
  }
};

const takeUntil = function(array, callback) {
  let results = [];
  for (let element of array) {
    if (!callback(element)) {
      results.push(element);
    } else {
      return results;
    }
  }
  return results;
};

//will return a slice of the array with elemetns taken from the beginning; keeps going until callback returns a truthy value

const data1 = [1, 2, 5, 7, 2, -1, 2, 4, 5];
const results1 = takeUntil(data1, x => x < 0);
assertArraysEqual(results1, [1, 2, 5, 7, 2]);

console.log('---');

const data2 = ["I've", "been", "to", "Hollywood", ",", "I've", "been", "to", "Redwood"];
const results2 = takeUntil(data2, x => x === ',');
assertArraysEqual(results2, ["I've", "been", "to", "Hollywood"]);