freeCodeCamp Challenge Guide: Falsy Bouncer

please could you explain me this code?
thanks

6 Likes

@dahider2 which do you need help with, the Advanced solution or @HarinaPana’s solution?

Beginner/Intermediate solution:

function bouncer(arr) {
 //Only return values that evaluate as true inside the array.
  return arr.filter(function(value){
    if (value){
      return (value);
    }
  });
}
14 Likes

I am talking about @HarinaPana solutions

Hope this helps:

function bouncer(arr) {

   function truthy(value) {
      //only return the given value if it evaluates as true. 
      //For example, 2, "string", true, will all return, but false, NaN, -1 will not.

      return value;
   }

   var filtered = arr.filter(truthy);
      //This is filtering only the values that evaluate as true in the given array (following the truthy function give above)

      return filtered;
 }

 //The function is now run with a given array, returning only the values that evaluate as true

 bouncer([7, "ate", "", false, 9]);
11 Likes
function bouncer(arr) {
// Don't show a false ID to this bouncer.
    return arr.filter(function(val) {
        return !!val ;
});
}
8 Likes

Super basic solution using forEach and push. Checks all values for true and pushes true ones into a new array.

function bouncer(arr) {
  var a = [];
  arr.forEach(function(el){
  if(el){
    a.push(el);}});
 return a;}
15 Likes

I managed it with this

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

I was far, very far from the easy solution given in this topic :slight_smile:

there’s no solution, there’s solutionS
Myself – Just now

16 Likes

I came very close…

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

Damn… could have condensed it down a line. Programmers want to get back to our Geekdom pursuits. Less lines = more time gaming

4 Likes

lol I used a bit different approach, here is the code:

function badValues(val){  
 return val !== false && val !== null && val !== 0 && val !== "" && val !== undefined && !Number.isNaN(val);   
}

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

bouncer([1, null, NaN, 2, undefined]);
8 Likes

My solution was a little longer, but it made a lot more sense to me and actually didn’t take long at all.

My code is pasted below, but essentially, I made a loop which would go through each element of the array and put it through a boolean operator to see if it was true. If it’s true, then push that element to a new array called noFalsy. Then, it filters the new noFalsy array for any values of null, because the nature of this particular loop means that if you have items in the middle of your array that are false but perhaps one at the end that is true, all of those false values will become null values in the new array.

function bouncer(arr) {
  
  var noFalsy = [];
  for (i = 0; i < arr.length; i++) {
    var x = Boolean(arr[i]);
    if (x === true) {
      noFalsy[i] = arr[i];
    } else {
    }
  }
  //filters function and removes any items that are null
  var noFalsyFinal = noFalsy.filter(function(noFalsy){
    return noFalsy !== null;
  });

  return noFalsyFinal;
  
}

bouncer([7, "ate", "", false, 9]);
2 Likes

bit different but here is mine :slight_smile:

function bouncer(arr) {
// Don’t show a false ID to this bouncer.
var a=true;
var newArr=arr.filter(function(a){
return a;
});
return newArr;
}

bouncer([7, “ate”, “”, false, 9]);

2 Likes

My code looks like this,

    function bouncer(arr) {
      // Don't show a false ID to this bouncer.
      var newArr = arr.filter(function(element){
        if(Boolean(element)){
          return element;
        }
      });
      return newArr;
    }

Boolean(x) means that we take the value and transform it to boolean, as a result get true or false.

1 Like

Mine was similar but you can cut it down by just returning the filtered array, without needing newArr

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

1 Like

My code is:

function bouncer(arr) {
var answer = arr.filter(function(teste) {
return teste;
});
return answer;
}

But I don’t understand why _function(teste)_and myFunction(teste) doesn’t work.

Hi can you explain this code. How does it evaluate ‘el’ to true?

hey @HebleV. so in my code where i say

if(el){
 a.push(el);}});

since it is in a forEach loop it checks every element in the array. if(el) is the same as saying if(el===true) and if(!el) is the same as if(el===false)
and if el is true it gets pushed into new array called a.
does that help?

3 Likes

buddy u have missed a semicolon @ var newArr=[];

1 Like

function truthy(value) {
//only return the given value if it evaluates as true.
//For example, 2, “string”, true, will all return, but false, NaN, -1 will not.

  return value;

}

Why would it always return true??
Can please anyone explain.

my code:

function bouncer(arr) {
  return arr.filter(function(el) {
    return Boolean(el) !== false;
  });
}

2 Likes