Tips for eliminating empty trailing values and Carriage Returns from a JavaScript array

Question

Tips for eliminating empty trailing values and Carriage Returns from a JavaScript array

I needed a way to eliminate empty elements and Carriage Returns from the end of an array. Here's an example of what my array looks like:

Input arr:

['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r']

Desired Output:

['', 'Apple', '', 'Banana', '', 'Guava']

Explanation of trailing empty elements : There are no valid elements following the last one ('Guava' in this instance).

javascript arrays

Answer 1

Answer №1

There is no easy solution to this problem, just a simple loop that checks for the specific values you want to eliminate, either directly or using a regular expression. For example, if you want to remove empty strings and "\r":

while (array.length) {                      
    const last = array[array.length - 1];   
    if (last !== "" && last !== "\r") {     
        break;                             
    }
    --array.length;                         
}

Live Example:

const array = ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];
while(array.length) {                     
    const last = array[array.length - 1];   
    if (last !== "" && last !== "\r") {
        break;
    }
    --array.length;
}

console.log(array);

To remove trailing entries consisting only of whitespace characters, you can use the following logic:

while (array.length) {
    if (/\S/.test(array[array.length - 1])) { 
        break;
    }
    --array.length;
}

This code snippet checks if the last entry contains any non-whitespace character and stops as soon as it finds one.

Live Example:

const array = ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];
while(array.length) {
    if (/\S/.test(array[array.length - 1])) {
        break;
    }
    --array.length;
}

console.log(array);

Answer 2

There is no easy solution to this problem, just a simple loop that checks for the specific values you want to eliminate, either directly or using a regular expression. For example, if you want to remove empty strings and "\r":

while (array.length) {                      
    const last = array[array.length - 1];   
    if (last !== "" && last !== "\r") {     
        break;                             
    }
    --array.length;                         
}

Live Example:

const array = ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];
while(array.length) {                     
    const last = array[array.length - 1];   
    if (last !== "" && last !== "\r") {
        break;
    }
    --array.length;
}

console.log(array);

To remove trailing entries consisting only of whitespace characters, you can use the following logic:

while (array.length) {
    if (/\S/.test(array[array.length - 1])) { 
        break;
    }
    --array.length;
}

This code snippet checks if the last entry contains any non-whitespace character and stops as soon as it finds one.

Live Example:

const array = ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];
while(array.length) {
    if (/\S/.test(array[array.length - 1])) {
        break;
    }
    --array.length;
}

console.log(array);

Answer 3

Answer №2

To determine the final index, utilize the findLastIndex() function (referencing this post), and proceed to slice the array from 0 up to the last index + 1:

const arr = ['', 'Orange', '', 'Grapes', '', 'Mango', '', '', '', '\r'];

function findLastIndex(array, predicate) {
  const index = array.slice().reverse().findIndex(predicate);
  return index >= 0 ? array.length - 1 - index : index;
};

const result = arr.slice(0, findLastIndex(arr, o => o !== '' && o !== '\r') + 1);

console.log(result);

Answer 4

To determine the final index, utilize the findLastIndex() function (referencing this post), and proceed to slice the array from 0 up to the last index + 1:

const arr = ['', 'Orange', '', 'Grapes', '', 'Mango', '', '', '', '\r'];

function findLastIndex(array, predicate) {
  const index = array.slice().reverse().findIndex(predicate);
  return index >= 0 ? array.length - 1 - index : index;
};

const result = arr.slice(0, findLastIndex(arr, o => o !== '' && o !== '\r') + 1);

console.log(result);

Answer 5

Answer №3

One effective approach to solving this issue involves utilizing the built-in Array.prototype.reduceRight() method to identify the final valid element.

const inputData = ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];
const outputData = [...inputData];

// checks if array element is valid
const isValidElement = elem => (typeof elem === 'string') && elem.length && elem !== '\r';

// locate last valid element
const lastValidElement = outputData.reduceRight((isValid, current, index) => {
  return isValid ||
    (isValidElement(current) ? index : undefined);
 }, undefined);

// trim the array accordingly
if (lastValidElement !== undefined) {
  outputData.length = lastValidElement + 1;
}

console.log(JSON.stringify(outputData));

Answer 6

One effective approach to solving this issue involves utilizing the built-in Array.prototype.reduceRight() method to identify the final valid element.

const inputData = ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];
const outputData = [...inputData];

// checks if array element is valid
const isValidElement = elem => (typeof elem === 'string') && elem.length && elem !== '\r';

// locate last valid element
const lastValidElement = outputData.reduceRight((isValid, current, index) => {
  return isValid ||
    (isValidElement(current) ? index : undefined);
 }, undefined);

// trim the array accordingly
if (lastValidElement !== undefined) {
  outputData.length = lastValidElement + 1;
}

console.log(JSON.stringify(outputData));

Answer 7

Answer №4

let fruitArray =['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];

function filterFruits(array){
  let filteredArray = [];
  let temporaryArray = array.join('').replace(/(\r)/, "").split(/(?=[A-Z])/);
  temporaryArray.forEach(item=>{
    filteredArray.push('',item);
  });
  return(filteredArray);
}
console.log(filterFruits(fruitArray));// prints ["", "Apple", "", "Banana", "", "Guava"]

Purpose of the function:

Initialize a new empty array.

let filteredArray = [];

Concatenates the elements of the array into a string, then removes any carriage returns and splits the string at uppercase characters.

let temporaryArray = array.join('').replace(/(\r)/, "").split(/(?=[A-Z])/);

Loop through the elements of the temporary array and add an empty character followed by each element to the filteredArray.

temporaryArray.forEach(item=>{
    filteredArray.push('',item);
  });

Answer 8

let fruitArray =['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r'];

function filterFruits(array){
  let filteredArray = [];
  let temporaryArray = array.join('').replace(/(\r)/, "").split(/(?=[A-Z])/);
  temporaryArray.forEach(item=>{
    filteredArray.push('',item);
  });
  return(filteredArray);
}
console.log(filterFruits(fruitArray));// prints ["", "Apple", "", "Banana", "", "Guava"]

Purpose of the function:

Initialize a new empty array.

let filteredArray = [];

Concatenates the elements of the array into a string, then removes any carriage returns and splits the string at uppercase characters.

let temporaryArray = array.join('').replace(/(\r)/, "").split(/(?=[A-Z])/);

Loop through the elements of the temporary array and add an empty character followed by each element to the filteredArray.

temporaryArray.forEach(item=>{
    filteredArray.push('',item);
  });

Answer 9

Answer №5

Using the reduceRight method, one can implement a logic where a reducer function gathers array items without requiring further validation once it encounters the first valid item (starting from the end of the array).

The starting point for this process is a collector object that stores all the necessary information for the reducer function, including the list where the selected array items are stored...

function collectValidItemFromRight(collector, item) {
  if (collector.isSkipValidation === true) {

    collector.list.unshift(item);
    
  } else if (collector.isValidItem(item)) {

    collector.list.unshift(item);
    collector.isSkipValidation = true;
  }
  return collector;
}

console.log(
  ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r']
    .reduceRight(collectValidItemFromRight, {

      isValidItem: item => (item !== '') && (item !== '\r'),
      list: [],

    }).list
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

Answer 10

Using the reduceRight method, one can implement a logic where a reducer function gathers array items without requiring further validation once it encounters the first valid item (starting from the end of the array).

The starting point for this process is a collector object that stores all the necessary information for the reducer function, including the list where the selected array items are stored...

function collectValidItemFromRight(collector, item) {
  if (collector.isSkipValidation === true) {

    collector.list.unshift(item);
    
  } else if (collector.isValidItem(item)) {

    collector.list.unshift(item);
    collector.isSkipValidation = true;
  }
  return collector;
}

console.log(
  ['', 'Apple', '', 'Banana', '', 'Guava', '', '', '', '\r']
    .reduceRight(collectValidItemFromRight, {

      isValidItem: item => (item !== '') && (item !== '\r'),
      list: [],

    }).list
);

.as-console-wrapper { min-height: 100%!important; top: 0; }

Tips for eliminating empty trailing values and Carriage Returns from a JavaScript array

Answer №1

Answer №2

Answer №3

Answer №4

Answer №5

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