freeCodeCamp/guide/english/certifications/javascript-algorithms-and-data-structures/basic-algorithm-scripting/falsy-bouncer/index.md

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Falsy Bouncer

Falsy Bouncer

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Problem Explanation

Remove all falsy values from an array.

Relevant Links

• Falsy Values

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Hints

Hint 1

Falsy is something which evaluates to FALSE. There are only six falsy values in JavaScript: undefined, null, NaN, 0, "" (empty string), and false of course.

Hint 2

We need to make sure we have all the falsy values to compare, we can know it, maybe with a function with all the falsy values...

Hint 3

Then we need to add a filter() with the falsy values function...

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Solutions

Solution 1 (Click to Show/Hide)

function bouncer(arr) {
  let newArray = [];
  for (var i = 0; i < arr.length; i++) {
    if (arr[i]) newArray.push(arr[i]);
  }
  return newArray;
}

Code Explanation

• We create a new empty array.
• We use a for cycle to iterate over all elements of the provided array (arr).
• We use the if statement to check if the current element is truthy or falsy.
• If the element is truthy, we push it to the new array (newArray). This result in the new array (newArray) containing only truthy elements.
• We return the new array (newArray).

Relevant Links

• Boolean
• Truthy value
• Falsey values
• Array.prototype.push

Solution 2 (Click to Show/Hide)

function bouncer(arr) {
  return arr.filter(Boolean);
}

Code Explanation

• The Array.prototype.filter method expects a function that returns a Boolean value which takes a single argument and returns true for truthy value or false for falsy value. Hence we pass the built-in Boolean function.

Relevant Links

• Boolean
• Truthy
• Array.prototype.filter()