Develop Reference

How to convert string to camelCase without using RegEX

I'm trying to do a challenge which is converting all strings into camelCase but without using regex, only using the methods like(split, slice, replace, includes.. etc). Some words have spaces and should remove them. Here's the CODE and I'm really STUCK. NOTE: the user enters the STRING and when user clicks the button should return to the camelCase.
INPUT =>
//underscore_case
//first_name
//Some_Variable
// calculate_AGE
//delayed_departure
OUTPUT =>
//underscoreCase
//firstName
//someVariable
//calculateAge
//delayedDeparture
document.body.append(document.createElement('textarea'));
document.body.append(document.createElement('button'));
document.querySelector('button').addEventListener('click', function() {
const text = document.querySelector('textarea').value;
const row = text.split('\n');
let [...n] = '';
for (const theText of row) {
const lowerText = theText.toLowerCase().trim();
if (lowerText.includes('_')) {
n = lowerText.replace('_', ' ');
console.log([...n]);
}
}
});

Explanation of this simple algorithm:
Your input must have words that split by a certain character, as you need something to identify which part of the string is a word. Let's assume your string has words separated by '//' instead of spaces as you mentioned in the comments, and each of those words is split by '_'.
First you need to split all words in the string into an array, you can use the split() method in order to do that.
Then when iterating through each word, split it again with split() but this time with whatever identifies the different words, in our case it's _.
Iterate through each split words, if it's the first word lowercase it using toLowerCase() and add it to the new word variable, if not, lowercase it and capitalize the first letter.
And that's it. Here's the implementation:
const inputWithoutCamelCase = 'hello_world // HOW_ARE_YOU // foo_BAR'
function stringToCamelCase(string) {
const allNames = string.split('//')
let camelCasedString = '';
for (const name of allNames) {
camelCasedString += nameToCamelCaseHelper(name);
}
return camelCasedString;
}
function nameToCamelCaseHelper(word) {
const splittedName = word.split('_');
let camelCasedName = '';
for (let i = 0; i < splittedName.length; i++) {
if (i === 0) {
camelCasedName += splittedName[i].toLowerCase();
} else {
camelCasedName += capitalizeFirstLetter(splittedName[i].toLowerCase())
}
}
return camelCasedName;
}
function capitalizeFirstLetter(string) {
return string.charAt(0).toUpperCase() + string.slice(1);
}
stringToCamelCase(inputWithoutCamelCase) // helloWorld howAreYou fooBar

Javascript - Replace a character inside a substring of a string

I have a string like "this/ is an example abc/def/fgh/uio to give you an example"
I'd like to target the longest word and replace on this substring any "/" by a "+".
I manage to identify the longest word and I would know how to replace ALL "/" by a "+" BUT I don't know how to replace the "/" only in the longest word.
Here's what I've got so far
//identify longest word in string
function longestWord(str) {
var words = str.split(' ');
return words.reduce(longer);
}
function longer(champ, contender) {
return (contender.length > champ.length) ? contender: champ;
}
//purely given an exemple, some strigns won't be exactly like this
var text2 = "this/ is an example abc/def/fgh/uio to give you an example"
if (longestWord(text2) > 30 ) {
text2.replace(/\//g, ' / ');
}
The problem is this will also replace the "/" on the substring "this/", and I don't want that.
How to achieve this?

Your longestWord function returns the longest word in the string, so you can pass that string alone (not a regular expression) as the first argument to .replace, and replace with (the second argument) the /\//g called on that longest word:
function getLongestWord(str) {
var words = str.split(' ');
return words.reduce(longer);
}
function longer(champ, contender) {
return (contender.length > champ.length) ? contender: champ;
}
var text2 = "this/ is an example abc/def/fgh/uio to give you an example"
const longestWord = getLongestWord(text2);
const output = text2.replace(longestWord, longestWord.replace(/\//g, '+'));
console.log(output);

#CertainPermance's solution is far more elegant (and I think performant) than this, but as I'd written the answer I thought I may as well put it in.
It's fairly similar, in truth, though in this instance we get the index of the word and use that to perform the replace, which at the time of writing I thought was necessary. Now looking at the better solution, I realise such a check is not needed, as the longest word in a string will not feature in any other words, so it's easy and safe to simply perform a replace on it.
const data = "this/ is an example abc/def/fgh/uio to give you an example";
const getLongestWordIndex = stringIn => stringIn
.split(' ')
.reduce(
(prev, curr, i) => curr.length > prev.length ? {
index: i,
length: curr.length
} : prev,
{
length: -1,
index: -1
}
).index
const replaceLongestWord = (sentence, replacer) => {
const longestWordIndex = getLongestWordIndex(sentence);
const words = data.split(' ');
return Object.values({
...words,
[longestWordIndex]: replacer(words[longestWordIndex])
}).join(' ')
}
const wordReplaceFunction = word => word.replace(/\//g, '+')
const result = replaceLongestWord(data, wordReplaceFunction);
console.dir(result)

Split and replace text by two rules (regex)

I trying to split text by two rules:
Split by whitespace
Split words greater than 5 symbols into two separate words like (aaaaawww into aaaaa- and www)
I create regex that can detect this rules (https://regex101.com/r/fyskB3/2) but can't understand how to make both rules work in (text.split(/REGEX/)
Currently regex - (([\s]+)|(\w{5})(?=\w))
For example initial text is hello i am markopollo and result should look like ['hello', 'i', 'am', 'marko-', 'pollo']

It would probably be easier to use .match: match up to 5 characters that aren't whitespace:
const str = 'wqerweirj ioqwejr qiwejrio jqoiwejr qwer qwer';
console.log(
str.match(/[^ ]{1,5}/g)
)

My approach would be to process the string before splitting (I'm a big fan of RegEx):
1- Search and replace all the 5 consecutive non-last characters with \1-.
The pattern (\w{5}\B) will do the trick, \w{5} will match 5 exact characters and \B will match only if the last character is not the ending character of the word.
2- Split the string by spaces.
var text = "hello123467891234 i am markopollo";
var regex = /(\w{5}\B)/g;
var processedText = text.replace(regex, "$1- ");
var result = processedText.split(" ");
console.log(result)
Hope it helps!

Something like this should work:
const str = "hello i am markopollo";
const words = str.split(/\s+/);
const CHUNK_SIZE=5;
const out = [];
for(const word of words) {
if(word.length > CHUNK_SIZE) {
let chunks = chunkSubstr(word,CHUNK_SIZE);
let last = chunks.pop();
out.push(...chunks.map(c => c + '-'),last);
} else {
out.push(word);
}
}
console.log(out);
// credit: https://stackoverflow.com/a/29202760/65387
function chunkSubstr(str, size) {
const numChunks = Math.ceil(str.length / size)
const chunks = new Array(numChunks)
for (let i = 0, o = 0; i < numChunks; ++i, o += size) {
chunks[i] = str.substr(o, size)
}
return chunks
}
i.e., first split the string into words on spaces, and then find words longer than 5 chars and 'chunk' them. I popped off the last chunk to avoid adding a - to it, but there might be a more efficient way if you patch chunkSubstr instead.
regex.split doesn't work so well because it will basically remove those items from the output. In your case, it appears you want to strip the whitespace but keep the words, so splitting on both won't work.

Uses the regex expression of #CertainPerformance = [^\s]{1,5}, then apply regex.exec, finally loop all matches to reach the goal.
Like below demo:
const str = 'wqerweirj ioqwejr qiwejrio jqoiwejr qwer qwer'
let regex1 = RegExp('[^ ]{1,5}', 'g')
function customSplit(targetString, regexExpress) {
let result = []
let matchItem = null
while ((matchItem = regexExpress.exec(targetString)) !== null) {
result.push(
matchItem[0] + (
matchItem[0].length === 5 && targetString[regexExpress.lastIndex] && targetString[regexExpress.lastIndex] !== ' '
? '-' : '')
)
}
return result
}
console.log(customSplit(str, regex1))
console.log(customSplit('hello i am markopollo', regex1))

How can I replace multiple characters in a string?

I want to create a regex with following logic:
1., If string contains T replace it with space
2., If string contains Z remove Z
I wrote two regex already, but I can't combine them:
string.replace(/\T/g,' ') && string.replace(/\Z/g,'');
EDIT: I want the regex code to be shorter

Doesn't seem this even needs regex. Just 2 chained replacements would do.
var str = '[T] and [Z] but not [T] and [Z]';
var result = str.replace('T',' ').replace('Z','');
console.log(result);
However, a simple replace only replaces the first occurence.
To replace all, regex still comes in handy. By making use of the global g flag.
Note that the characters aren't escaped with \. There's no need.
var str = '[T] and [Z] and another [T] and [Z]';
var result = str.replace(/T/g,' ').replace(/Z/g,'');
console.log(result);
// By using regex we could also ignore lower/upper-case. (the i flag)
// Also, if more than 1 letter needs replacement, a character class [] makes it simple.
var str2 = '(t) or (Ⓣ) and (z) or (Ⓩ). But also uppercase (T) or (Z)';
var result2 = str2.replace(/[tⓉ]/gi,' ').replace(/[zⓏ]/gi,'');
console.log(result2);
But if the intention is to process really big strings, and performance matters?
Then I found out in another challenge that using an unnamed callback function inside 1 regex replace can prove to be faster. When compared to using 2 regex replaces.
Probably because if it's only 1 regex then it only has to process the huge string once.
Example snippet:
console.time('creating big string');
var bigstring = 'TZ-'.repeat(2000000);
console.timeEnd('creating big string');
console.log('bigstring length: '+bigstring.length);
console.time('double replace big string');
var result1 = bigstring.replace(/[t]/gi,'X').replace(/[z]/gi,'Y');
console.timeEnd('double replace big string');
console.time('single replace big string');
var result2 = bigstring.replace(/([t])|([z])/gi, function(m, c1, c2){
if(c1) return 'X'; // if capture group 1 has something
return 'Y';
});
console.timeEnd('single replace big string');
var smallstring = 'TZ-'.repeat(5000);
console.log('smallstring length: '+smallstring.length);
console.time('double replace small string');
var result3 = smallstring.replace(/T/g,'X').replace(/Z/g,'Y');
console.timeEnd('double replace small string');
console.time('single replace small string');
var result4 = smallstring.replace(/(T)|(Z)/g, function(m, c1, c2){
if(c1) return 'X';
return 'Y';
});
console.timeEnd('single replace small string');

Do you look for something like this?
ES6
var key = {
'T': ' ',
'Z': ''
}
"ATAZATA".replace(/[TZ]/g, (char) => key[char] || '');
Vanilla
"ATAZATA".replace(/[TZ]/g,function (char) {return key[char] || ''});
or
"ATAZATA".replace(/[TZ]/g,function (char) {return char==='T'?' ':''});

you can capture both and then decide what to do in the callback:
string.replace(/[TZ]/g,(m => m === 'T' ? '' : ' '));
var string = 'AZorro Tab'
var res = string.replace(/[TZ]/g,(m => m === 'T' ? '' : ' '));
console.log(res)
-- edit --
Using a dict substitution you can also do:
var string = 'AZorro Tab'
var dict = { T : '', Z : ' '}
var re = new RegExp(`[${ Object.keys(dict).join('') }]`,'g')
var res = string.replace(re,(m => dict[m] ) )
console.log(res)

Second Update
I have developed the following function to use in production, perhaps it can help someone else. It's basically a loop of the native's replaceAll Javascript function, it does not make use of regex:
function replaceMultiple(text, characters){
for (const [i, each] of characters.entries()) {
const previousChar = Object.keys(each);
const newChar = Object.values(each);
text = text.replaceAll(previousChar, newChar);
}
return text
}
Usage is very simple:
const text = '#Please send_an_information_pack_to_the_following_address:';
const characters = [
{
"#":""
},
{
"_":" "
},
]
const result = replaceMultiple(text, characters);
console.log(result); //'Please send an information pack to the following address:'
Update
You can now use replaceAll natively.
Outdated Answer
Here is another version using String Prototype. Enjoy!
String.prototype.replaceAll = function(obj) {
let finalString = '';
let word = this;
for (let each of word){
for (const o in obj){
const value = obj[o];
if (each == o){
each = value;
}
}
finalString += each;
}
return finalString;
};
'abc'.replaceAll({'a':'x', 'b':'y'}); //"xyc"

Split sentence by space mixed up my index

I'm facing some problem while trying to send text to some spelling API.
The API return the corrections based on the words index, for example:
sentence:
"hello hoow are youu"
So the API index the words by numbers like that and return the correction based on that index:
0 1 2 3
hello hoow are youu
API Response that tell me which words to correct:
1: how
3: you
On the code I using split command to break the sentence into words array so I will be able to replace the misspelled words by their index.
string.split(" ");
My problem is that the API trim multiple spaces between words into one space, and by doing that the API words index not match my index. (I would like to preserve the spaces on the final output)
Example of the problem, sentence with 4 spaces between words:
Hello howw are youu?
0 1 2 3 4 5 6 7
hello hoow are youu
I thought about looping the words array and determine if the element is word or space and then create something new array like that:
indexed_words[0] = hello
indexed_words[0_1] = space
indexed_words[0_2] = space
indexed_words[0_3] = space
indexed_words[0_4] = space
indexed_words[0_5] = space
indexed_words[0_6] = space
indexed_words[0_7] = space
indexed_words[1] = how
indexed_words[2] = are
indexed_words[3] = you?
That way I could replace the misspelled words easily and than rebuild the sentence back with join command but the problem but the problem that I cannot use non-numeric indexes (its mixed up the order of the array)
Any idea how I can keep the formatting (spaces) but still correct the words?
Thanks

in that case you have very simple solution:L
$(document).ready(function(){
var OriginalSentence="howw are you?"
var ModifiedSentence="";
var splitstring=OriginalSentence.split(' ')
$.each(splitstring,function(i,v){
if(v!="")
{
//pass this word to your api and appedn it to sentance
ModifiedSentence+=APIRETURNVALUE//api return corrected value;
}
else{
ModifiedSentence+=v;
}
});
alert(ModifiedSentence);
});

Please review this one:
For string manipulation like this, I would highly recommend you to use Regex
Use online regex editor for faster try and error like here https://regex101.com/.
here I use /\w+/g to match every words if you want to ignore 1 or two words we can use /\w{2,}/g or something like that.
var str = "Hello howw are youu?";
var re = /\w+/g
var words = str.match(re);
console.log("Returning valus")
words.forEach(function(word, index) {
console.log(index + " -> " + word);
})
Correction
Just realize that you need to keep spacing as it is, please try this one:
I used your approach to change all to space. create array for its modified version then send to your API (I dunno that part). Then get returned data from API, reconvert it back to its original formating string.
var ori = `asdkhaskd asdkjaskdjaksjd askdjaksdjalsd a ksjdhaksjdhasd asdjkhaskdas`;
function replaceMeArr(str, match, replace) {
var s = str,
reg = match || /\s/g,
rep = replace || ` space `;
return s.replace(reg, rep).split(/\s/g);
}
function replaceMeStr(arr, match, replace) {
var a = arr.join(" "),
reg = match || /\sspace\s/g,
rep = replace || " ";
return a.replace(reg, rep);
}
console.log(`ori1: ${ori}`);
//can use it like this
var modified = replaceMeArr(ori);
console.log(`modi: ${modified.join(' ')}`);
//put it back
var original = replaceMeStr(modified);
console.log(`ori2: ${original}`);

Updated
var str = "Hello howw are youu?";
var words = str.split(" ");
// Getting an array without spaces/empty values
// send it to your API call
var requestArray = words.filter(function(word){
if (word) {
return word;
}
});
console.log("\nAPI Response that tell me which words to correct:");
console.log("6: how\n8: you");
var response = {
"1": "how",
"3": "you"
}
//As you have corrected words index, Replace those words in your "requestArray"
for (var key in response) {
requestArray[key] = response[key];
}
//now we have array of non-empty & correct spelled words. we need to put back empty (space's) value back in between this array
var count = 0;
words.forEach(function(word, index){
if (word) {
words[index] = requestArray[count];
count++;
}
})
console.log(words);
Correct me, if i was wrong.
Hope this helps :)

Try this JSFiddle
, Happy coding :)
//
// ReplaceMisspelledWords
//
// Created by Hilal Baig on 21/11/16.
// Copyright © 2016 Baigapps. All rights reserved.
//
var preservedArray = new Array();
var splitArray = new Array();
/*Word Object to preserve my misspeled words indexes*/
function preservedObject(pIndex, nIndex, title) {
this.originalIndex = pIndex;
this.apiIndex = nIndex;
this.title = title;
}
/*Preserving misspeled words indexes in preservedArray*/
function savePreserveIndexes(str) {
splitArray = str.split(" ");
//console.log(splitArray);
var x = 0;
for (var i = 0; i < splitArray.length; i++) {
if (splitArray[i].length > 0) {
var word = new preservedObject(i, x, splitArray[i]);
preservedArray.push(word);
x++;
}
}
};
function replaceMisspelled(resp) {
for (var key in resp) {
for (var i = 0; i < preservedArray.length; i++) {
wObj = preservedArray[i];
if (wObj.apiIndex == key) {
wObj.title = resp[key];
splitArray[wObj.originalIndex] = resp[key];
}
}
}
//console.log(preservedArray);
return correctedSentence = splitArray.join(" ");
}
/*Your input string to be corrected*/
str = "Hello howw are youu";
console.log(str);
savePreserveIndexes(str);
/*API Response in json of corrected words*/
var apiResponse = '{"1":"how","3":"you" }';
resp = JSON.parse(apiResponse);
//console.log(resp);
/*Replace misspelled words by corrected*/
console.log(replaceMisspelled(resp)); //Your solution