We Keep Coding

Get the last capitalized letter from a string

I need to get the last uppercase letter from the string and wondering how can I do it. I want to write a function that takes the string and returns the last uppercase letter from that string.
For example, If I call the function with word 'LonDon', I should get D. And if I call the function with word 'CaliforNia', I get N.
Thank you so much for your time.

function findLastCap(text) {
let length = text.length - 1;
for (let i = length; i >= 0; i--) {
if (text[i] !== text[i].toLowerCase()) return text[i];
}
return false;
}
console.log(findLastCap("aaaaaaBccc"))

Use a Regular Expression, probably [A-Z](?=[^A-Z]*$)
[A-Z]: match any capital letter
(?=[^A-Z]*$): Followed by any # of non-uppercase and the end of the string.
let regex = /[A-Z](?=[^A-Z]*$)/;
console.log({
CaliforNia: 'CaliforNia'.match(regex)[0],
LonDon: 'LonDon'.match(regex)[0]
});

I do not know javascript but I can help you come up with an algorithm that would solve this problem.
First I will write it in python3 and explain what I did and you can try to translate it into javascript.
def last_upper(string):
last = "" # i make a string var here
for let in string:
if let.issupper():
last = let
return last
So basically what I did in this code is that I iterate through all the elements in the string and if a letter is uppercase it will update the last variable. It works because it keeps on updating it each time it finds a uppercase letter.

Try this,
let reg = /[A-Z](?=[^A-Z]*$)/g
let p = "Parts spaR";
p.match(reg)
Or you can get all the matches and access the last one,
let reg = /[A-Z]/g
let r = p.match(reg)
let found = r[r.length-1]

let tempString=`aaaaaBcCcF`;
let result = tempString.split('').filter(value => {
let str = '';
if (value === value.toUpperCase()) {
str = value;
}
return str;
})
console.log(result[result.length-1]);

What am I missing regarding the toUpperCase method?

I am trying to make the first letter of each word capitalized via toUpperCase method and the rest of the word is in the lower case via the toLowerCase method. But I am missing something... Why temp value is not matching with result[1][0] even if I am using that method for both?
Note: I know about other ways (map, replace, etc) for my solution, but I want to just use a for-loop with toUpperCase and toLowerCase methods.
function titleCase(str) {
let regex = /[^0-9\s]+/g;
var result = str.match(regex);
let temp = "";
for (let i = 0; i < result.length; i++) {
for (let j = 0; j < result[i].length; j++) {
result[1][0] = result[1][0].toUpperCase();
temp = result[1][0].toUpperCase();
}
}
console.log(temp); // Output is 'A'
console.log(result[1][0]); //Output is 'a'
// Normally 'temp' and 'result[1][0]' should be equal, but one returns a lowercase character and the other an uppercase character.
return str;
}
titleCase("I'm a little tea pot");

Your problem is not with the toUppercase(), it is with the reference.
When referencing result[1][0], why are you including the 0? You already have the second character with result[1]
result[1] === 'a'. No need to include the [0] as well.
Change your code so it looks like this:
function titleCase(str) {
let regex = /[^0-9\s]+/g;
var result = str.match(regex);
let temp = "";
result[1] = result[1].toUpperCase();
temp = result[1].toUpperCase();
console.log(temp); // Output is 'A'
console.log(result[1]); //Output is also 'A'
// both now equals capital A
return str;
}
titleCase("I'm a little tea pot");
EDIT:
Updating the function to uppercase the first letter of the word.
We can use ES6, which would make this really simple:
const capitalize = (string = '') => [...string].map((char, index) => index ? char : char.toUpperCase()).join('')
Use it: capitalize("hello") returns 'Hello'.
First we convert the string to an array, using the spread operator, to get each char individually as a string. Then we map each character to get the index to apply the uppercase to it. Index true means not equal 0, so (!index) is the first character. We then apply the uppercase function to it and then return the string.
If you want a more object oriented approach, we can do something like this:
String.prototype.capitalize = function(allWords) {
return (allWords) ?
this.split(' ').map(word => word.capitalize()).join(' ') :
return this.charAt(0).toUpperCase() + this.slice(1);
}
Use it: "hello, world!".capitalize(); returns "Hello, World"
We break down the phrase to words and then recursive calls until capitalising all words. If allWords is undefined, capitalise only the first word meaning the first character of the whole string.

I was tried to change a specific character in the string but strings are immutable in JS so this does not make sense.

RegExp "i" case insensitive VS toLowerCase() (javascript)

I'm hoping someone can explain to me why I need to use "toLowerCase()" if I'm already using a regular expression that is case insensitive "i".
The exercise is a pangram that can accept numbers and non-ascii characters, but all letters of the alphabet MUST be present in lower case, upper case, or mixed. I wasn't able to solve this exercise correctly until I added "toLowerCase()". This is one of the javascript exercises from exercism.io. Below is my code:
var Pangram = function (sentence) {
this.sentence = sentence;
};
Pangram.prototype.isPangram = function (){
var alphabet = "abcdefghijklmnopqrstuvwxyz", mustHave = /^[a-z]+$/gi,
x = this.sentence.toLowerCase(), isItValid = mustHave.test(x);
for (var i = 0; i < alphabet.length; i++){
if (x.indexOf(alphabet[i]) === -1 && isItValid === false){
return false;
}
}
return true;
};
module.exports = Pangram;

The regex may not be doing what you think it's doing. Here is your code commented with what's going on:
Pangram.prototype.isPangram = function (){
var alphabet = "abcdefghijklmnopqrstuvwxyz", mustHave = /^[a-z]+$/gi,
x = this.sentence.toLowerCase(), isItValid = mustHave.test(x);
// for every letter in the alphabet
for (var i = 0; i < alphabet.length; i++){
// check the following conditions:
// letter exists in the sentence (case sensitive)
// AND sentence contains at least one letter between a-z (start to finish, case insensitive)
if (x.indexOf(alphabet[i]) === -1 && isItValid === false){
return false;
}
}
return true;
}
The logic that is checking whether each letter is present has nothing to do with the regex, the two are serving separate purposes. In fact, based on your description of the problem, the regex will cause your solution to fail in some cases. For example, assume we have the string "abcdefghijklmnopqrstuvwxyz-". In that case your regex will test false even though this sentence should return true.
My advice would be to remove the regex, use toLowerCase on the sentence, and iterate through the alphabet checking if the sentence has each letter - which you seems to be the track you were on.
Below is a sample solution with some tests. Happy learning!
function isPangram (str) {
const alphabet = 'abcdefghijklmnopqrstuvwxyz'
const strChars = new Set(str.toLowerCase().split(''))
return alphabet.split('').every(char => strChars.has(char))
}
const tests = [
"abc",
"abcdefghijklmnopqrstuvwxyz",
"abcdefghijklmnopqRstuvwxyz",
"abcdefghijklmnopqRstuvwxyz-",
]
tests.forEach(test => {
console.log(test, isPangram(test))
})

It's because you're manually checking for lowercase letters:
if (x.indexOf(alphabet[i]) === -1)
alphabet[i] will be one of your alphabet string, which you have defined as lowercase.
It looks like you don't need the regex at all here, or at least it's not doing what you think it's doing. Since your regex only allows for alpha characters, it will fail if your sentence has any spaces.

Javascript IndexOf with integers in string not working

Can anyone tell me why does this not work for integers but works for characters? I really hate reg expressions since they are cryptic but will if I have too. Also I want to include the "-()" as well in the valid characters.
String.prototype.Contains = function (str) {
return this.indexOf(str) != -1;
};
var validChars = '0123456789';
var str = $("#textbox1").val().toString();
if (str.Contains(validChars)) {
alert("found");
} else {
alert("not found");
}

Review
String.prototype.Contains = function (str) {
return this.indexOf(str) != -1;
};
This String "method" returns true if str is contained within itself, e.g. 'hello world'.indexOf('world') != -1would returntrue`.
var validChars = '0123456789';
var str = $("#textbox1").val().toString();
The value of $('#textbox1').val() is already a string, so the .toString() isn't necessary here.
if (str.Contains(validChars)) {
alert("found");
} else {
alert("not found");
}
This is where it goes wrong; effectively, this executes '1234'.indexOf('0123456789') != -1; it will almost always return false unless you have a huge number like 10123456789.
What you could have done is test each character in str whether they're contained inside '0123456789', e.g. '0123456789'.indexOf(c) != -1 where c is a character in str. It can be done a lot easier though.
Solution
I know you don't like regular expressions, but they're pretty useful in these cases:
if ($("#textbox1").val().match(/^[0-9()]+$/)) {
alert("valid");
} else {
alert("not valid");
}
Explanation
[0-9()] is a character class, comprising the range 0-9 which is short for 0123456789 and the parentheses ().
[0-9()]+ matches at least one character that matches the above character class.
^[0-9()]+$ matches strings for which ALL characters match the character class; ^ and $ match the beginning and end of the string, respectively.
In the end, the whole expression is padded on both sides with /, which is the regular expression delimiter. It's short for new RegExp('^[0-9()]+$').

Assuming you are looking for a function to validate your input, considering a validChars parameter:
String.prototype.validate = function (validChars) {
var mychar;
for(var i=0; i < this.length; i++) {
if(validChars.indexOf(this[i]) == -1) { // Loop through all characters of your string.
return false; // Return false if the current character is not found in 'validChars' string.
}
}
return true;
};
var validChars = '0123456789';
var str = $("#textbox1").val().toString();
if (str.validate(validChars)) {
alert("Only valid characters were found! String validates!");
} else {
alert("Invalid Char found! String doesn't validate.");
}
However, This is quite a load of code for a string validation. I'd recommend looking into regexes, instead. (Jack's got a nice answer up here)

You are passing the entire list of validChars to indexOf(). You need to loop through the characters and check them one-by-one.
Demo
String.prototype.Contains = function (str) {
var mychar;
for(var i=0; i<str.length; i++)
{
mychar = this.substr(i, 1);
if(str.indexOf(mychar) == -1)
{
return false;
}
}
return this.length > 0;
};
To use this on integers, you can convert the integer to a string with String(), like this:
var myint = 33; // define integer
var strTest = String(myint); // convert to string
console.log(strTest.Contains("0123456789")); // validate against chars

I'm only guessing, but it looks like you are trying to check a phone number. One of the simple ways to change your function is to check string value with RegExp.
String.prototype.Contains = function(str) {
var reg = new RegExp("^[" + str +"]+$");
return reg.test(this);
};
But it does not check the sequence of symbols in string.
Checking phone number is more complicated, so RegExp is a good way to do this (even if you do not like it). It can look like:
String.prototype.ContainsPhone = function() {
var reg = new RegExp("^\\([0-9]{3}\\)[0-9]{3}-[0-9]{2}-[0-9]{2}$");
return reg.test(this);
};
This variant will check phones like "(123)456-78-90". It not only checks for a list of characters, but also checks their sequence in string.

Thank you all for your answers! Looks like I'll use regular expressions. I've tried all those solutions but really wanted to be able to pass in a string of validChars but instead I'll pass in a regex..
This works for words, letters, but not integers. I wanted to know why it doesn't work for integers. I wanted to be able to mimic the FilteredTextBoxExtender from the ajax control toolkit in MVC by using a custom Attribute on a textBox

Remove all special characters except space from a string using JavaScript

I want to remove all special characters except space from a string using JavaScript.
For example,
abc's test#s
should output as
abcs tests.

You should use the string replace function, with a single regex.
Assuming by special characters, you mean anything that's not letter, here is a solution:
const str = "abc's test#s";
console.log(str.replace(/[^a-zA-Z ]/g, ""));

You can do it specifying the characters you want to remove:
string = string.replace(/[&\/\\#,+()$~%.'":*?<>{}]/g, '');
Alternatively, to change all characters except numbers and letters, try:
string = string.replace(/[^a-zA-Z0-9]/g, '');

The first solution does not work for any UTF-8 alphabet. (It will cut text such as Привіт). I have managed to create a function which does not use RegExp and use good UTF-8 support in the JavaScript engine. The idea is simple if a symbol is equal in uppercase and lowercase it is a special character. The only exception is made for whitespace.
function removeSpecials(str) {
var lower = str.toLowerCase();
var upper = str.toUpperCase();
var res = "";
for(var i=0; i<lower.length; ++i) {
if(lower[i] != upper[i] || lower[i].trim() === '')
res += str[i];
}
return res;
}
Update: Please note, that this solution works only for languages where there are small and capital letters. In languages like Chinese, this won't work.
Update 2: I came to the original solution when I was working on a fuzzy search. If you also trying to remove special characters to implement search functionality, there is a better approach. Use any transliteration library which will produce you string only from Latin characters and then the simple Regexp will do all magic of removing special characters. (This will work for Chinese also and you also will receive side benefits by making Tromsø == Tromso).

search all not (word characters || space):
str.replace(/[^\w ]/, '')

I don't know JavaScript, but isn't it possible using regex?
Something like [^\w\d\s] will match anything but digits, characters and whitespaces. It would be just a question to find the syntax in JavaScript.

I tried Seagul's very creative solution, but found it treated numbers also as special characters, which did not suit my needs. So here is my (failsafe) tweak of Seagul's solution...
//return true if char is a number
function isNumber (text) {
if(text) {
var reg = new RegExp('[0-9]+$');
return reg.test(text);
}
return false;
}
function removeSpecial (text) {
if(text) {
var lower = text.toLowerCase();
var upper = text.toUpperCase();
var result = "";
for(var i=0; i<lower.length; ++i) {
if(isNumber(text[i]) || (lower[i] != upper[i]) || (lower[i].trim() === '')) {
result += text[i];
}
}
return result;
}
return '';
}

const str = "abc's#thy#^g&test#s";
console.log(str.replace(/[^a-zA-Z ]/g, ""));

Try to use this one
var result= stringToReplace.replace(/[^\w\s]/g, '')
[^] is for negation, \w for [a-zA-Z0-9_] word characters and \s for space,
/[]/g for global

With regular expression
let string = "!#This tool removes $special *characters* /other/ than! digits, characters and spaces!!!$";
var NewString= string.replace(/[^\w\s]/gi, '');
console.log(NewString);
Result //This tool removes special characters other than digits characters and spaces
Live Example : https://helpseotools.com/text-tools/remove-special-characters

dot (.) may not be considered special. I have added an OR condition to Mozfet's & Seagull's answer:
function isNumber (text) {
reg = new RegExp('[0-9]+$');
if(text) {
return reg.test(text);
}
return false;
}
function removeSpecial (text) {
if(text) {
var lower = text.toLowerCase();
var upper = text.toUpperCase();
var result = "";
for(var i=0; i<lower.length; ++i) {
if(isNumber(text[i]) || (lower[i] != upper[i]) || (lower[i].trim() === '') || (lower[i].trim() === '.')) {
result += text[i];
}
}
return result;
}
return '';
}

Try this:
const strippedString = htmlString.replace(/(<([^>]+)>)/gi, "");
console.log(strippedString);

const input = `#if_1 $(PR_CONTRACT_END_DATE) == '23-09-2019' #
Test27919<alerts#imimobile.com> #elseif_1 $(PR_CONTRACT_START_DATE) == '20-09-2019' #
Sender539<rama.sns#gmail.com> #elseif_1 $(PR_ACCOUNT_ID) == '1234' #
AdestraSID<hello#imimobile.co> #else_1#Test27919<alerts#imimobile.com>#endif_1#`;
const replaceString = input.split('$(').join('->').split(')').join('<-');
console.log(replaceString.match(/(?<=->).*?(?=<-)/g));

Whose special characters you want to remove from a string, prepare a list of them and then user javascript replace function to remove all special characters.
var str = 'abc'de#;:sfjkewr47239847duifyh';
alert(str.replace("'","").replace("#","").replace(";","").replace(":",""));
or you can run loop for a whole string and compare single single character with the ASCII code and regenerate a new string.