Develop Reference

Delete special characters from an ng-repeat list (parsed from CSV) [duplicate]

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.

How to split a string at commas but ignore \,?

I want to split string http://some.com/\,brabra,400,500 into ['http://some.com/\,brabra', 400, 500]
I already tried this, but error because lookbehind is not support in js.
'http://some.com/\,brabra,400,500'.split(/(?<!\\),/g)
Any other ideas to do this?

You may use matching approach with (?:[^,\\]+|\\.)+:
match(/(?:[^,\\]+|\\.)+/g)
See the regex demo
Details: the (?:[^,\\]+|\\.)+ matches 1 or more occurrences ((?:...)+) of a 1+ characters other than , and \ (with [^,\\]+) or (|) any escaped sequence (\\.)
var s = "http://some.com/\\,brabra,400,500"
console.log(s.match(/(?:[^,\\]+|\\.)+/g));
Or a workaround if the comma to be split with is always followed with a digit:
split(/,(?=\d)/)
See this regex demo
var s = "http://some.com/\\,brabra,400,500"
console.log(s.split(/,(?=\d)/));

A classic, if slightly inelegant approach for such problems is to replace some characters with a magic token, then put them back later:
str
.replace("\\,", "DONT_SPLIT_HERE")
.split(',')
.map(part => part.replace("DONT_SPLIT_HERE", "\\,")

you can use simulate positive lookaheads with reversing the string:
String.prototype.reverse = function() {
return this.split("").reverse().join("");
}
Array.prototype.reverseElements = function() {
var ar = [];
for (var i = 0; i < this.length; i++) {
if (typeof this[i] === 'string')
ar[i] = this[i].reverse();
else {
//Do something if not a String
}
}
return ar;
}
var str = "http://some.com/\,brabra,400,500";
var ar = str.reverse().split(/,(?!\\)/).reverse().reverseElements();
console.log(ar);
Note: The Regex works here, but not in the snippet.

Underscore replace in javascript

I have a string
var string = "aa--'aa____\_____abccc".
I want to replace all underscores with single space. How can I do this using javascript?
I don't want to use any regular expression. Please suggest the possible ways.

You can replace all duplicate underscores with single underscores, then replace all underscores with spaces:
while (string.indexOf('__') != -1) {
string = string.replace('__', '_');
}
while (string.indexOf('_') != -1) {
string = string.replace('_', ' ');
}
Another way would be to loop through the string and check for underscores and output a space for the first underscore in a group:
var result = '';
var space = false;
for (var i = 0; i < string.length; i++) {
if (string[i] == '_') {
if (!space) {
result += ' ';
}
space = true;
} else {
result += string[i];
space = false;
}
}
This would of course be simpler and much more efficient using a regular expression:
string = string.replace(/_+/g, ' ');
Note: If you expect the result to have a backslash, that won't happen. There is no backslash in the string to start with, the character combination \_ is interpreted as a _. If you want to put a backslash in the string you would use \\ in the string literal.

var string = "aa--'aa \ abccc".
done

JavaScript return only regex from string

This might be pretty simple, but I am having a hard time with it. Consider the following code:
var string = 'testingT#$^%#$ESTING__--232'
string = string.match(/^\w*$/)
if (string != null)
{
string = string.join('')
string = string.toUpperCase()
}
$('#my-input').val(string)
What I want to do, is to strip all characters that aren't alphanumeric or underscore from string, and then transform that string to uppercase.
So far I did that, it works perfectly if I don't add any special characters, but when I add - or ^ to it, for example, it deletes everything from #my-input

You can do this in one step:
string = string.replace(/[^\w]/g, '').toUpperCase();
console.log(string); //=> "TESTINGTESTING__232"

var string = string.replace(/[^a-zA-Z_0-9]/g,'').toUpperCase()
Also, do you need unicode? My regex will only match a-z, and not åÉø for example.

You need use 'global' flag in regex and remove match restriction.
var str = 'testingT#$^%#$ESTING__--232';
str = str.match(/\w+/g);
if (str !== null)
{
str = str.join('');
str = str.toUpperCase();
}
$('#my-input').val(str);

javascript code to check special characters

I have JavaScript code to check if special characters are in a string. The code works fine in Firefox, but not in Chrome. In Chrome, even if the string does not contain special characters, it says it contains special characters.
var iChars = "~`!#$%^&*+=-[]\\\';,/{}|\":<>?";
for (var i = 0; i < chkfile.value.length; i++)
{
if (iChars.indexOf(chkfile.value.charAt(i)) != -1)
{
alert ("File name has special characters ~`!#$%^&*+=-[]\\\';,/{}|\":<>? \nThese are not allowed\n");
return false;
}
}
Suppose I want to upload a file desktop.zip from any Linux/Windows machine.
The value of chkfile.value is desktop.zip in Firefox, but in Chrome the value of chkfile.value is c://fakepath/desktop.zip. How do I get rid of c://fakepath/ from chkfile.value?

You can test a string using this regular expression:
function isValid(str){
return !/[~`!#$%\^&*+=\-\[\]\\';,/{}|\\":<>\?]/g.test(str);
}

Try This one.
function containsSpecialCharacters(str){
var regex = /[ !##$%^&*()_+\-=\[\]{};':"\\|,.<>\/?]/g;
return regex.test(str);
}

Directly from the w3schools website:
var str = "The best things in life are free";
var patt = new RegExp("e");
var res = patt.test(str);
To combine their example with a regular expression, you could do the following:
function checkUserName() {
var username = document.getElementsByName("username").value;
var pattern = new RegExp(/[~`!#$%\^&*+=\-\[\]\\';,/{}|\\":<>\?]/); //unacceptable chars
if (pattern.test(username)) {
alert("Please only use standard alphanumerics");
return false;
}
return true; //good user input
}

Did you write return true somewhere? You should have written it, otherwise function returns nothing and program may think that it's false, too.
function isValid(str) {
var iChars = "~`!#$%^&*+=-[]\\\';,/{}|\":<>?";
for (var i = 0; i < str.length; i++) {
if (iChars.indexOf(str.charAt(i)) != -1) {
alert ("File name has special characters ~`!#$%^&*+=-[]\\\';,/{}|\":<>? \nThese are not allowed\n");
return false;
}
}
return true;
}
I tried this in my chrome console and it worked well.

You could also do it this way.
specialRegex = /[^A-Z a-z0-9]/
specialRegex.test('test!') // evaluates to true
Because if its not a capital letter, lowercase letter, number, or space, it could only be a special character

If you don't want to include any special character, then try this much simple way for checking special characters using RegExp \W Metacharacter.
var iChars = "~`!#$%^&*+=-[]\\\';,/{}|\":<>?";
if(!(iChars.match(/\W/g)) == "") {
alert ("File name has special characters ~`!#$%^&*+=-[]\\\';,/{}|\":<>? \nThese are not allowed\n");
return false;
}