Algorithm Falsy Bouncer in CodeCamp

Question

Algorithm Falsy Bouncer in CodeCamp

What is the reason this works for all falsy values except null?

 function bouncer(arr) {
  for(let i = 0; i < arr.length; i++){
    if(!arr[i]){
      arr.splice(i,1);
      i = 0;
    }
 }
   console.log(arr);
}

bouncer([false, null, 0, NaN, undefined, ""])

javascript arrays boolean

Answer 1

Answer №1

When working with a for loop, the final expression that occurs, such as i++ in this case, will always be executed after the loop body. This means that regardless of the input array, the value of i will be reset to 0 only at the beginning of the first iteration:

function bouncer(arr) {
  for (let i = 0; i < arr.length; i++) {
    console.log('i:', i);
    if (!arr[i]) {
      arr.splice(i, 1);
      i = 0;
    }
  }
  console.log(arr);
}

console.log(bouncer([false, null, 0, NaN, undefined, ""]));

To address this, you could reset i to -1 instead, causing it to become 0 again at the start of the next loop iteration:

function bouncer(arr) {
  for (let i = 0; i < arr.length; i++) {
    console.log('i:', i);
    if (!arr[i]) {
      arr.splice(i, 1);
      i = -1;
    }
  }
  console.log(arr);
}

console.log(bouncer([false, null, 0, NaN, undefined, ""]));

Alternatively, you can simplify the logic by using .filter instead. The .filter method provides a more straightforward solution:

const bouncer = arr => arr.filter(Boolean);
console.log(bouncer([false, null, 0, NaN, undefined, ""]));

Answer 2

When working with a for loop, the final expression that occurs, such as i++ in this case, will always be executed after the loop body. This means that regardless of the input array, the value of i will be reset to 0 only at the beginning of the first iteration:

function bouncer(arr) {
  for (let i = 0; i < arr.length; i++) {
    console.log('i:', i);
    if (!arr[i]) {
      arr.splice(i, 1);
      i = 0;
    }
  }
  console.log(arr);
}

console.log(bouncer([false, null, 0, NaN, undefined, ""]));

To address this, you could reset i to -1 instead, causing it to become 0 again at the start of the next loop iteration:

function bouncer(arr) {
  for (let i = 0; i < arr.length; i++) {
    console.log('i:', i);
    if (!arr[i]) {
      arr.splice(i, 1);
      i = -1;
    }
  }
  console.log(arr);
}

console.log(bouncer([false, null, 0, NaN, undefined, ""]));

Alternatively, you can simplify the logic by using .filter instead. The .filter method provides a more straightforward solution:

const bouncer = arr => arr.filter(Boolean);
console.log(bouncer([false, null, 0, NaN, undefined, ""]));

Answer 3

Answer №2

alternatively, you have the option to utilize

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

Answer 4

alternatively, you have the option to utilize

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

Answer 5

Answer №3

Adding to the input from DeterminedExpert, another approach is to manage the increase of i within the loop itself, as shown below:

function filterFalsyValues(arr)
{
  for (let i = 0; i < arr.length;)
  {
    console.log('i:', i);

    if (!arr[i])
      arr.splice(i, 1);
    else
      i++;
  }

  return arr;
}

console.log(filterFalsyValues([false, null, 0, "Another value", NaN, undefined, ""]));

Answer 6

Adding to the input from DeterminedExpert, another approach is to manage the increase of i within the loop itself, as shown below:

function filterFalsyValues(arr)
{
  for (let i = 0; i < arr.length;)
  {
    console.log('i:', i);

    if (!arr[i])
      arr.splice(i, 1);
    else
      i++;
  }

  return arr;
}

console.log(filterFalsyValues([false, null, 0, "Another value", NaN, undefined, ""]));

Answer 7

Answer №4

When using arr.splice(i,1), keep in mind that the value of i is the same as the outer loop. Therefore, setting it to 0 will not be effective. To ensure the correct deletion, subtract 1 from i like this: arr.splice(i--,1) so that the shifted entry is not overlooked.

function filterFalsy(arr) {

  for(let i=0; i < arr.length; i++){
  
    if(!(arr[i]))
      arr.splice(i--,1);
  }   
  return arr;
}

console.log(filterFalsy([false, null, 0, NaN, undefined, ""]));

Answer 8

When using arr.splice(i,1), keep in mind that the value of i is the same as the outer loop. Therefore, setting it to 0 will not be effective. To ensure the correct deletion, subtract 1 from i like this: arr.splice(i--,1) so that the shifted entry is not overlooked.

function filterFalsy(arr) {

  for(let i=0; i < arr.length; i++){
  
    if(!(arr[i]))
      arr.splice(i--,1);
  }   
  return arr;
}

console.log(filterFalsy([false, null, 0, NaN, undefined, ""]));

Answer 9

Answer №5

const filterFalsyValues = (arr) => {
    return arr.filter(item => item);
}
console.log(filterFalsyValues([false, 0, null, NaN, undefined, ""]));

This function filters out falsy values from an array based on their truthiness.

Answer 10

const filterFalsyValues = (arr) => {
    return arr.filter(item => item);
}
console.log(filterFalsyValues([false, 0, null, NaN, undefined, ""]));

This function filters out falsy values from an array based on their truthiness.

Algorithm Falsy Bouncer in CodeCamp

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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