Differences between JavaScript array manipulation using the split(" ") method and the spread operator

Question

Differences between JavaScript array manipulation using the split(" ") method and the spread operator

I'm currently attempting to determine if a given sentence is a palindrome, disregarding word breaks and punctuation.

The code snippet that utilizes cStr.split(" ") DOES NOT achieve the desired outcome. Although it splits on whitespaces (" "), calling reverse() seems ineffective in this case.

const palindromes = (str) => {
    const regex = /[!"#$%&'()*+,-./:;<=>?@[\]^_`{|}~]/g;
    const cStr = str.toLowerCase().replace(regex, "").split(" ").join("");
    const revStr = cStr.split(" ").slice().reverse().join("");
    return cStr === revStr ? true : false;
};

FURTHER CONSIDERATIONS: Upon joining the original string cStr at the end, the characters appear collapsed. In the flawed code example, splitting on "whitespace" (split(" ")) triggers the script to halt without throwing any errors?

The same logic applied with either [...cStr] or cStr.split("") DOES yield the intended result:

const revStr = cStr.split("").slice().reverse().join("");

// or
const revStr = [...cStr].slice().reverse().join("");

How does the choice of "separator" - /""/ or /" "/ impact this behavior?

If the separator is an empty string (""), the string is converted into an array of individual UTF-16 "characters", excluding empty strings at the ends.

Linked inquiry regarding array manipulation: reverse-array-in-javascript-without-mutating-original-array

Related query concerning string handling: character-array-from-string

Documentation for Split(): String.prototype.split()

javascript arrays slice reverse

Answer 1

Answer №1

It appears that you have reviewed the documentation for string.split, but may not have fully grasped its nuances. When splitting a string with a separator that does not exist in the string, it returns an array with one element containing the entire string. However, if you split by an empty separator, it will divide the string after every character.

let astring = "nowhitespacehere";
let splitstring1 = astring.split(" ");
console.log(splitstring1);
let splitstring2 = astring.split("");
console.log(splitstring2);

Your initial method removes all white spaces from the string using

str.split(" ").join("");

Later on, you perform

cStr.split(" ").slice().reverse().join("");

If you break down those steps:

.split(" ") by whitespace. Since there are no whitespaces, this results in an array with one element: [cStr]
You .slice() this array, creating another 1-element array: [cStr]
You .reverse() this 1-element array, yielding yet another 1-element array: [cStr]
You finally .join("") the elements in this 1-element array with an empty separator to obtain cStr

In your alternate approach, you execute

cStr.split("").slice().reverse().join("");

The key distinction is the initial split("") which splits the string after every character

Your first method does not "stop executing"; rather, it behaves as instructed - splitting by a non-existent separator. There is no reason for this action to throw an error, as it follows the intended functionality of the split method. It concatenates characters until a separator is found, and if none exists, the entire string becomes the token...

Answer 2

It appears that you have reviewed the documentation for string.split, but may not have fully grasped its nuances. When splitting a string with a separator that does not exist in the string, it returns an array with one element containing the entire string. However, if you split by an empty separator, it will divide the string after every character.

let astring = "nowhitespacehere";
let splitstring1 = astring.split(" ");
console.log(splitstring1);
let splitstring2 = astring.split("");
console.log(splitstring2);

Your initial method removes all white spaces from the string using

str.split(" ").join("");

Later on, you perform

cStr.split(" ").slice().reverse().join("");

If you break down those steps:

.split(" ") by whitespace. Since there are no whitespaces, this results in an array with one element: [cStr]
You .slice() this array, creating another 1-element array: [cStr]
You .reverse() this 1-element array, yielding yet another 1-element array: [cStr]
You finally .join("") the elements in this 1-element array with an empty separator to obtain cStr

In your alternate approach, you execute

cStr.split("").slice().reverse().join("");

The key distinction is the initial split("") which splits the string after every character

Your first method does not "stop executing"; rather, it behaves as instructed - splitting by a non-existent separator. There is no reason for this action to throw an error, as it follows the intended functionality of the split method. It concatenates characters until a separator is found, and if none exists, the entire string becomes the token...

Answer 3

Answer №2

After reviewing your initial function and looking through @derpirscher's response, I made some optimizations to enhance its efficiency. I didn't want to discard it completely, so here are my thoughts as additional inspiration.

When dealing with palindromes, the comparison is at the letter level, eliminating the need to break the sentence into individual words.

const checkPalindrome = (str) => {
    const regex = /[^a-zA-Z]/g; 
    const cleanStr = str.toLowerCase().replace(regex, ""); 
    const reversedStr = cleanStr.split("").reverse().join("");
    return cleanStr === reversedStr; 
};

Answer 4

After reviewing your initial function and looking through @derpirscher's response, I made some optimizations to enhance its efficiency. I didn't want to discard it completely, so here are my thoughts as additional inspiration.

When dealing with palindromes, the comparison is at the letter level, eliminating the need to break the sentence into individual words.

const checkPalindrome = (str) => {
    const regex = /[^a-zA-Z]/g; 
    const cleanStr = str.toLowerCase().replace(regex, ""); 
    const reversedStr = cleanStr.split("").reverse().join("");
    return cleanStr === reversedStr; 
};

Differences between JavaScript array manipulation using the split(" ") method and the spread operator

Answer №1

Answer №2

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