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Caps and Lowercase input that also generates in output

I've been trying to put together an input where the text automatically capitalizes the first letter of each word and makes all other letters lowercase for that word. I had some success using that for just making everything lower case after the first letter for the input with this:
<input type = "text" size="8" name="textfield1" id="textfield1" />
with the javascript being
document.getElementById('textfield1').addEventListener("keyup", () => {
var inputValue = document.getElementById('textfield1')['value'];
if (inputValue[0] === ' ') {
inputValue = '';
} else if (inputValue) {
inputValue = inputValue[0].toUpperCase() + inputValue.slice(1).toLowerCase();
}
document.getElementById('textfield1')['value'] = inputValue;
});
I tried adding map(), split(), and join() in various ways based off of lessons I've found (I'm learning on my own, no formal training since high school) for use in a string with the console.log methods but I'm confused on how I can apply this to an input. It would take too long to note everything I've tried but one thing I did was this:
document.getElementById('textfield1').addEventListener("keyup", () => {
var inputValue = document.getElementById('textfield1')['value'];
if (inputValue[0] === ' ') {
inputValue = '';
} else if (inputValue) {
input.content = input.content.split(' ').map(function(inputValue) {
return inputValue[0].toUpperCase() + inputValue.slice(1).toLowerCase();
}).join(' ');
}
document.getElementById('textfield1')['value'] = inputValue;
});
I'm not sure what I'm missing here. I'm sure there's something that I'm not seeing or understanding. I also tried looking to see if there was something similar listed on here or elsewhere in relation to this and inputs but I didn't see anything specific to what I was looking for.
I want the input to remain the same for what comes up with the output into another box when it gets copied over.
Example of what I'm trying to do is:
input of textfield: heLlo OuT thERe!
output to another textarea with the click of a button: Hello Out There!

Your second version would be correct. However in this code:
else if (inputValue) {
input.content = input.content.split(' ').map(function(inputValue) {
return inputValue[0].toUpperCase() + inputValue.slice(1).toLowerCase();
}).join(' ');
}
You started to use some input.content instead of the inputValue variable. Most probably yout mistake lies there.

You can use this regex replace to change a sentence to Proper Case:
const regex = /\b(\w)(\w*)/g;
const input = 'Fix this lower and UPPER to Proper'
let result = input.replace(regex, function(m, c1, c2) {
return c1.toUpperCase() + c2.toLowerCase()
});
console.log('result: ', result);
// => 'Fix This Lower And Upper To Proper'
Explanation of regex:
\b -- word boundary
(\w) -- capture group 1: a singe word character
(\w*) --capture group 2: zero to multiple word characters
g -- flag for global, e.g. run pattern multiple times
replace function: parameter c1 contains capture group 1, c2 contains capture group 2

How do I replace the last letter of a string element in an array with replace()

I've just started coding..I'm a super beginner and have no idea about regex yet so for now I'd rather not use it. This is an exercise I'm trying to solve. The problem is that when a word contains matching characters, the first character gets the lower case, but what I actually want is the last character of the word to become small.
I don't really require a solution for the problem. Instead I'd rather have some insight on what I'm doing wrong and maybe direct me to the right path :)
function alienLanguage(str) {
let bigWords = str.toUpperCase().split(" ");
let lastLetterSmall = [];
bigWords.forEach(words => {
lastLetterSmall
.push(words
.replace(words
.charAt(words.length -1), words.charAt(words.length -1).toLowerCase()));
});
console.log(lastLetterSmall.join(' '));
}
alienLanguage("My name is John");
alienLanguage("this is an example");
alienLanguage("Hello World");
alienLanguage("HELLO WORLD");

Since you only really want to work with indicies of the string - you don't need to replace anything dynamically other than the last index - replace won't work well, since if you pass it a string, it will only replace the first matching letter. For example:
'foo'.replace('o', 'x')
results in 'fxo', because the first o (and only the first o) gets replaced.
For your code, instead of replace, just concatenate the two parts of the string together: the part from index 0 to next-to-last index, and the character at the last index with toLowerCase() called on it:
function alienLanguage(str) {
const result = str
.toUpperCase()
.split(" ")
.map(line => line.slice(0, line.length - 1) + line[line.length - 1].toLowerCase())
.join(' ');
console.log(result);
}
alienLanguage("My name is John");
alienLanguage("this is an example");
alienLanguage("Hello World");
alienLanguage("HELLO WORLD");

Algorithm - Search and Replace a string

I am doing a algorithm in freeCodeCamp.(https://www.freecodecamp.org/learn/javascript-algorithms-and-data-structures/intermediate-algorithm-scripting/search-and-replace)
The task is as below:
Perform a search and replace on the sentence using the arguments provided and return the new sentence.
First argument is the sentence to perform the search and replace on.
Second argument is the word that you will be replacing (before).
Third argument is what you will be replacing the second argument with (after).
Note:
Preserve the case of the first character in the original word when you are replacing it. For example if you mean to replace the word "Book" with the word "dog", it should be replaced as "Dog"
**
myReplace("Let us get back to more Coding", "Coding", "algorithms") should return "Let us get back to more Algorithms".
myReplace("Let us go to the store", "store", "mall") should return "Let us go to the mall".
**
//if the before is uppercase, the after should be uppercase also
// str = str.replace(before, after);
var regex = /[A-Z]+/g; //check for uppercase
var newStr = "";
console.log(regex.test(before));
if (regex.test(before)) {
//if uppercase, return true, "after" convert to uppercase
after = after.toUpperCase();
newStr = after[0];
for (var i = 1; i < after.length; i++) {
//start at index=1 letter, all convert to
newStr += after[i].toLowerCase();
}
console.log(newStr);
str = str.replace(before, newStr);
} else {
str = str.replace(before, after);
}
// console.log(newStr);
console.log(str);
return str;
}
I think there should be OK for the code, but can anyone help find why the if statement can't work.
Much thanks!

The problem is that you're calling regex.test() multiple times on the same regular expression instance.
[...]
var regex = /[A-Z]+/g; //check for uppercase
var newStr = "";
console.log(regex.test(before));
if (regex.test(before)) {
//if uppercase, return true, "after" convert to uppercase
after = after.toUpperCase();
[...]
If your string is Hello_there, the first regex.test() will return true, because Hello matched. If you call regex.test() again with the same regex instance, it will have advanced in the string, and try to match starting with _there. In this case, it will fail, because _there does not begin with a capital letter between A and Z.
There are a lot of ways to fix this issue. Perhaps the simplest is to store the result of the first call to a variable, and use it everywhere you're calling regex.test():
[...]
var regex = /[A-Z]+/g; //check for uppercase
var newStr = "";
var upper_check = regex.test(before);
console.log(upper_check);
if (upper_check) {
[...]

It seems overkill to use a regex, when you really need to only check the first character. Your regex will find uppercase letters anywhere...
If the assignment is to only change one occurrence, then a regex is not really the right tool here: it does not really help to improve the code nor the efficiency. Just do:
function myReplace(str, before, after) {
if (before[0] === before[0].toUpperCase()) {
after = after[0].toUpperCase() + after.slice(1);
} else {
after = after[0].toLowerCase() + after.slice(1);
}
return str.replace(before, after);
}

function myReplace(str, before, after) {
var upperRegExp = /[A-Z]/g
var lowerRegExp = /[a-z]/g
var afterCapitalCase = after.replace(/^./, after[0].toUpperCase());
if (before[0].match(upperRegExp)) {
return str.replace(before, afterCapitalCase)
} else if (after[0].match(upperRegExp) && before[0].match(lowerRegExp)) {
return str.replace(before, after.toLowerCase());
} else {
return str.replace(before, after)
}
}

Capitalizing first letter after special character or letter

I am new to either Javascript or regex. I need to replace first word letter to the capital letter and my code does it, but it's also replacing the letter after special character or other letter (like ąčęėįš or etc.) and somehow I need to avoid it and change just only first letter. Could someone help me to solve this problem?
My code is here:
function capitalizeName(input) {
var name = input.val();
name = name.toLowerCase().replace(/\b[a-z]/g, function(letter) {
return letter.toUpperCase();
})
input.val(name);

I prefer a non-regex answer to all such questions, for fun and mostly you don't need complex regexes
"java script is cool".split(" ").map(function(w){return w[0].toUpperCase()+w.substr(1)}).join(" ")
"Java Script Is Cool"

Then you need to remove word boundary with space or start anchor match.
name = name.toLowerCase().replace(/(^|\s)[a-z]/g, function(letter) {
return letter.toUpperCase();
})

This should work for you:
or this
console.log("tihi is some rčęėįš random typing. Is it good? maby has some minor-bugs but at least works"
.replace(/\w.*?\W/g, x => x[0].toUpperCase() + x.substr(1)))
you have to add non world char at the end for this to work.
const data = "tihi is some rčęėįš random typing. Is it good? maby has some minor-bugs but at least works."
const capitalize = data => (data + ' ').replace(/\w.*?\W/g, x => x[0].toUpperCase() + x.substr(1)).substr(0, data.length)
console.log(capitalize(data))

How to account for punctuation and uppercase while counting the number of occurrences of a string in a sentence

I'm writing a function but cannot figure out how to account for upper case letter and punctuation.
My function is :
function countWords(word, string) {
var subStr = string.split(word);
return subStr.length - 1;
}
And it works when I try to test is with wordCount("hey","this is code hey"), but not if I try ("HEY", "this is code hey")
I tried
var subStr= string.toUpperCase().split(word)
but it will not work with lower case letters anymore.

Why can't you try like this.
function countWords(word, string) {
word= word.toLowerCase();
string=string.toLowerCase();
var subStr = string.split(word);
return subStr.length - 1;
}
So that whatever values we sent it will be converted into lower case then it will split.
Does it makes sense right?

Try this :
function countWords(word, string) {
var subStr = string.toLowerCase().split(word.toLowerCase());
return subStr.length - 1;
}
$(document).ready(function(){
$('#result').html(countWords("HEY","this is code hey"));
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div id="result"></div>

Try sending the parameter to either all upper or lower cases first so that it matches the case of the string you are comparing it to. For example,
function countWords(word.toLowerCase, string.toLowerCase)
That way the search is evaluated regardless of case.

You could use a regex with the i and g modifier (case insensitive/match all) and match, then return the length:
function wordCount(search, txt) {
var regex = new RegExp("\\W" + search + "\\W|\\W" + search, "ig");
var match = txt.match(regex);
return match ? match.length : 0;
}
console.log(wordCount("hey","this is code heyHey HEY hey")); // 2
If you want to have heyHey as 2 matches, simply remove |\\W" + search from the regex