[javascript] Trim specific character from a string

What's the JavaScript equivalent to this C# Method:

var x = "|f|oo||"; 
var y = x.Trim('|'); //  "f|oo"

C# trims the selected character only at the beginning and end of the string!

The best way to resolve this task is (similar with PHP trim function):

function trim( str, charlist ) {_x000D_
  if ( typeof charlist == 'undefined' ) {_x000D_
    charlist = '\\s';_x000D_
  }_x000D_
  _x000D_
  var pattern = '^[' + charlist + ']*(.*?)[' + charlist + ']*$';_x000D_
  _x000D_
  return str.replace( new RegExp( pattern ) , '$1' )_x000D_
}_x000D_
_x000D_
document.getElementById( 'run' ).onclick = function() {_x000D_
  document.getElementById( 'result' ).value = _x000D_
  trim( document.getElementById( 'input' ).value,_x000D_
  document.getElementById( 'charlist' ).value);_x000D_
}

<div>_x000D_
  <label for="input">Text to trim:</label><br>_x000D_
  <input id="input" type="text" placeholder="Text to trim" value="dfstextfsd"><br>_x000D_
  <label for="charlist">Charlist:</label><br>_x000D_
  <input id="charlist" type="text" placeholder="Charlist" value="dfs"><br>_x000D_
  <label for="result">Result:</label><br>_x000D_
  <input id="result" type="text" placeholder="Result" disabled><br>_x000D_
  <button type="button" id="run">Trim it!</button>_x000D_
</div>

P.S.: why i posted my answer, when most people already done it before? Because i found "the best" mistake in all of there answers: all used the '+' meta instead of '*', 'cause trim must remove chars IF THEY ARE IN START AND/OR END, but it return original string in else case.

String.prototype.TrimStart = function (n) {
    if (this.charAt(0) == n)
        return this.substr(1);
};

String.prototype.TrimEnd = function (n) {
    if (this.slice(-1) == n)
        return this.slice(0, -1);
};

If you define these functions in your program, your strings will have an upgraded version of trim that can trim all given characters:

String.prototype.trimLeft = function(charlist) {_x000D_
 if (charlist === undefined)_x000D_
 charlist = "\s";_x000D_
_x000D_
 return this.replace(new RegExp("^[" + charlist + "]+"), "");_x000D_
};_x000D_
_x000D_
String.prototype.trim = function(charlist) {_x000D_
 return this.trimLeft(charlist).trimRight(charlist);_x000D_
};_x000D_
_x000D_
String.prototype.trimRight = function(charlist) {_x000D_
 if (charlist === undefined)_x000D_
 charlist = "\s";_x000D_
_x000D_
 return this.replace(new RegExp("[" + charlist + "]+$"), "");_x000D_
};_x000D_
_x000D_
var withChars = "/-center-/"_x000D_
var withoutChars = withChars.trim("/-")_x000D_
document.write(withoutChars)

Source

https://www.sitepoint.com/trimming-strings-in-javascript/

expanding on @leaf 's answer, here's one that can take multiple characters:

var trim = function (s, t) {
  var tr, sr
  tr = t.split('').map(e => `\\\\${e}`).join('')
  sr = s.replace(new RegExp(`^[${tr}]+|[${tr}]+$`, 'g'), '')
  return sr
}

This one trims all leading and trailing delimeters

const trim = (str, delimiter) => {
  const pattern = `[^\\${delimiter}]`;
  const start = str.search(pattern);
  const stop = str.length - str.split('').reverse().join('').search(pattern);
  return str.substring(start, stop);
}

const test = '||2|aaaa12bb3ccc|||||';
console.log(trim(test, '|')); // 2|aaaa12bb3ccc

This can trim several characters at a time:

function trimChars (str, c) {
  var re = new RegExp("^[" + c + "]+|[" + c + "]+$", "g");
  return str.replace(re,"");
}

var x = "|f|oo||"; 
x =  trimChars(x, '|'); // f|oo

var y = "..++|f|oo||++..";
y = trimChars(y, '|.+'); // f|oo

var z = "\\f|oo\\"; // \f|oo\

// For backslash, remember to double-escape:
z = trimChars(z, "\\\\"); // f|oo

For use in your own script and if you don't mind changing the prototype, this can be a convenient "hack":

String.prototype.trimChars = function (c) {
  var re = new RegExp("^[" + c + "]+|[" + c + "]+$", "g");
  return this.replace(re,"");
}

var x = "|f|oo||"; 
x =  x.trimChars('|'); // f|oo

Since I use the trimChars function extensively in one of my scripts, I prefer this solution. But there are potential issues with modifying an object's prototype.

"|Howdy".replace(new RegExp("^\\|"),"");

(note the double escaping. \\ needed, to have an actually single slash in the string, that then leads to escaping of | in the regExp).

Only few characters need regExp-Escaping., among them the pipe operator.

To my knowledge, jQuery doesnt have a built in function the method your are asking about. With javascript however, you can just use replace to change the content of your string:

x.replace(/|/i, ""));

This will replace all occurences of | with nothing.

try:

console.log(x.replace(/\|/g,''));

I like the solution from @Pho3niX83...

Let's extend it with "word" instead of "char"...

function trimWord(_string, _word) {

    var splitted = _string.split(_word);

    while (splitted.length && splitted[0] === "") {
        splitted.shift();
    }
    while (splitted.length && splitted[splitted.length - 1] === "") {
        splitted.pop();
    }
    return splitted.join(_word);
};

I would suggest looking at lodash and how they implemented the trim function.

See Lodash Trim for the documentation and the source to see the exact code that does the trimming.

I know this does not provide an exact answer your question, but I think it's good to set a reference to a library on such a question since others might find it useful.

function trim(text, val) {
    return text.replace(new RegExp('^'+val+'+|'+val+'+$','g'), '');
}

to keep this question up to date:

here is an approach i'd choose over the regex function using the ES6 spread operator.

function trimByChar(string, character) {
  const first = [...string].findIndex(char => char !== character);
  const last = [...string].reverse().findIndex(char => char !== character);
  return string.substring(first, string.length - last);
}

Improved version after @fabian 's comment (can handle strings containing the same character only)

function trimByChar1(string, character) {
  const arr = Array.from(string);
  const first = arr.findIndex(char => char !== character);
  const last = arr.reverse().findIndex(char => char !== character);
  return (first === -1 && last === -1) ? '' : string.substring(first, string.length - last);
}

Try this method:

var a = "anan güzel mi?";_x000D_
if (a.endsWith("?"))   a = a.slice(0, -1);  _x000D_
document.body.innerHTML = a;

A regex-less version which is easy on the eye:

const trim = (str, chars) => str.split(chars).filter(Boolean).join(chars);

For use cases where we're certain that there's no repetition of the chars off the edges.

You can use a regular expression such as:

var x = "|f|oo||";
var y = x.replace(/^\|+|\|+$/g, "");
alert(y); // f|oo

UPDATE:

Should you wish to generalize this into a function, you can do the following:

var escapeRegExp = function(strToEscape) {
    // Escape special characters for use in a regular expression
    return strToEscape.replace(/[\-\[\]\/\{\}\(\)\*\+\?\.\\\^\$\|]/g, "\\$&");
};

var trimChar = function(origString, charToTrim) {
    charToTrim = escapeRegExp(charToTrim);
    var regEx = new RegExp("^[" + charToTrim + "]+|[" + charToTrim + "]+$", "g");
    return origString.replace(regEx, "");
};

var x = "|f|oo||";
var y = trimChar(x, "|");
alert(y); // f|oo

If you're dealing with longer strings I believe this should outperform most of the other options by reducing the number of allocated strings to either zero or one:

function trim(str, ch) {
    var start = 0, 
        end = str.length;

    while(start < end && str[start] === ch)
        ++start;

    while(end > start && str[end - 1] === ch)
        --end;

    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}

// Usage:
trim('|hello|world|', '|'); // => 'hello|world'

Or if you want to trim from a set of multiple characters:

function trimAny(str, chars) {
    var start = 0, 
        end = str.length;

    while(start < end && chars.indexOf(str[start]) >= 0)
        ++start;

    while(end > start && chars.indexOf(str[end - 1]) >= 0)
        --end;

    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}

// Usage:
trimAny('|hello|world   ', [ '|', ' ' ]); // => 'hello|world'
// because '.indexOf' is used, you could also pass a string for the 2nd parameter:
trimAny('|hello| world  ', '| '); // => 'hello|world'

EDIT: For fun, trim words (rather than individual characters)

// Helper function to detect if a string contains another string
//     at a specific position. 
// Equivalent to using `str.indexOf(substr, pos) === pos` but *should* be more efficient on longer strings as it can exit early (needs benchmarks to back this up).
function hasSubstringAt(str, substr, pos) {
    var idx = 0, len = substr.length;

    for (var max = str.length; idx < len; ++idx) {
        if ((pos + idx) >= max || str[pos + idx] != substr[idx])
            break;
    }

    return idx === len;
}

function trimWord(str, word) {
    var start = 0,
        end = str.length,
        len = word.length;

    while (start < end && hasSubstringAt(str, word, start))
        start += word.length;

    while (end > start && hasSubstringAt(str, word, end - len))
        end -= word.length

    return (start > 0 || end < str.length) ? str.substring(start, end) : str;
}

// Usage:
trimWord('blahrealmessageblah', 'blah');

If I understood well, you want to remove a specific character only if it is at the beginning or at the end of the string (ex: ||fo||oo|||| should become foo||oo). You can create an ad hoc function as follows:

function trimChar(string, charToRemove) {
    while(string.charAt(0)==charToRemove) {
        string = string.substring(1);
    }

    while(string.charAt(string.length-1)==charToRemove) {
        string = string.substring(0,string.length-1);
    }

    return string;
}

I tested this function with the code below:

var str = "|f|oo||";
$( "#original" ).html( "Original String: '" + str + "'" );
$( "#trimmed" ).html( "Trimmed: '" + trimChar(str, "|") + "'" );