JavaScript Cheat Sheet

JavaScript Cheat Sheet

// Regex
var myAllergies = /\bmy (seasonal )?allergies\b/i;
var text = 'My allergies are acting up. I need some medicine.';
if(text.search(myAllergies) > -1) {

}

// Object.defineProperty
function Car() {

}

Object.defineProperty(Car.prototype, 'color', {
  get: function() {
    return 'blue';
  }
});

// memoizer, fibonacci, factorial
function memoizer(memo, formula) {
  var recur = function (n) {
    var result = memo[n];
    if (typeof result !== 'number') {
      result = formula(recur, n);
      memo[n] = result;
    }
    return result;
  };
  return recur;
}

var fibonacci = memoizer([0, 1], function (recur, n) {
  return recur(n - 1) + recur(n - 2);
});

var factorial = memoizer([1, 1], function (recur, n) {
  return n * recur(n - 1);
});

function isPalindrome(word) {

  for (let i = 0; i < word.length/2; i++) {
    let first = word[i];
    let second = word[word.length - (i + 1)];
    if (first !== second) {
      return false;
    }
  }
  return true;
}