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

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Falsy Bouncer

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Problem Explanation:

Remove all falsy values from an array.

Relevant Links

• Falsy Values

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.

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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...

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Hint: 3

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

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Spoiler Alert!

Solution ahead!

Basic Code Solution:

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

Run Code

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

Advanced Code Solution:

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

Run Code

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()

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