[javascript] Replace multiple characters in one replace call

Very simple little question, but I don't quite understand how to do it.

I need to replace every instance of '_' with a space, and every instance of '#' with nothing/empty.

var string = '#Please send_an_information_pack_to_the_following_address:';

I've tried this:

string.replace('#','').replace('_', ' ');

I don't really like chaining commands like this. Is there another way to do it in one?

For replacing with nothing, tckmn's answer is the best.

If you need to replace with specific strings corresponding to the matches, here's a variation on Voicu's and Christophe's answers that avoids duplicating what's being matched, so that you don't have to remember to add new matches in two places:

const replacements = {
  '’': "'",
  '“': '"',
  '”': '"',
  '—': '---',
  '–': '--',
};
const replacement_regex = new RegExp(Object
  .keys(replacements)
  // escape any regex literals found in the replacement keys:
  .map(e => e.replace(/[.*+?^${}()|[\]\\]/g, '\\$&'))
  .join('|')
, 'g');
return text.replace(replacement_regex, e => replacements[e]);

Here's a simple way to do it without RegEx.
You can prototype and/or cache things as desired.

// Example: translate( 'faded', 'abcdef', '123456' ) returns '61454'
function translate( s, sFrom, sTo ){
    for ( var out = '', i = 0; i < s.length; i++ ){
        out += sTo.charAt( sFrom.indexOf( s.charAt(i) ));
    }
    return out;
}

String.prototype.replaceAll=function(obj,keydata='key'){
 const keys=keydata.split('key');
return Object.entries(obj).reduce((a,[key,val])=> a.replace(new RegExp(`${keys[0]}${key}${keys[1]}`,'g'),val),this)
}

const data='hids dv sdc sd {yathin} {ok}'
console.log(data.replaceAll({yathin:12,ok:'hi'},'{key}'))

String.prototype.replaceAll=function(keydata,obj){ const keys=keydata.split('key'); return Object.entries(obj).reduce((a,[key,val])=> a.replace(${keys[0]}${key}${keys[1]},val),this) }

const data='hids dv sdc sd ${yathin} ${ok}' console.log(data.replaceAll('${key}',{yathin:12,ok:'hi'}))

Please try:

• replace multi string

  var str = "http://www.abc.xyz.com"; str = str.replace(/http:|www|.com/g, ''); //str is "//.abc.xyz"

• replace multi chars

  var str = "a.b.c.d,e,f,g,h"; str = str.replace(/[.,]/g, ''); //str is "abcdefgh";

Good luck!

I don't know if how much this will help but I wanted to remove <b> and </b> from my string

so I used

mystring.replace('<b>',' ').replace('</b>','');

so basically if you want a limited number of character to be reduced and don't waste time this will be useful.

You can also pass a RegExp object to the replace method like

var regexUnderscore = new RegExp("_", "g"); //indicates global match
var regexHash = new RegExp("#", "g");

string.replace(regexHash, "").replace(regexUnderscore, " ");

Javascript RegExp

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"

Specify the /g (global) flag on the regular expression to replace all matches instead of just the first:

string.replace(/_/g, ' ').replace(/#/g, '')

To replace one character with one thing and a different character with something else, you can't really get around needing two separate calls to replace. You can abstract it into a function as Doorknob did, though I would probably have it take an object with old/new as key/value pairs instead of a flat array.

Chaining is cool, why dismiss it?

Anyway, here is another option in one replace:

string.replace(/#|_/g,function(match) {return (match=="#")?"":" ";})

The replace will choose "" if match=="#", " " if not.

[Update] For a more generic solution, you could store your replacement strings in an object:

var replaceChars={ "#":"" , "_":" " };
string.replace(/#|_/g,function(match) {return replaceChars[match];})

yourstring = '#Please send_an_information_pack_to_the_following_address:';

replace '#' with '' and replace '_' with a space

var newstring1 = yourstring.split('#').join('');
var newstring2 = newstring1.split('_').join(' ');

newstring2 is your result

If you want to replace multiple characters you can call the String.prototype.replace() with the replacement argument being a function that gets called for each match. All you need is an object representing the character mapping which you will use in that function.

For example, if you want a replaced with x, b with y and c with z, you can do something like this:

var chars = {'a':'x','b':'y','c':'z'};
var s = '234abc567bbbbac';
s = s.replace(/[abc]/g, m => chars[m]);
console.log(s);

Output: 234xyz567yyyyxz

Here is a "safe HTML" function using a 'reduce' multiple replacement function (this function applies each replacement to the entire string, so dependencies among replacements are significant).

// Test:
document.write(SafeHTML('<div>\n\
    x</div>'));

function SafeHTML(str)
    {
    const replacements = [
        {'&':'&amp;'},
        {'<':'&lt;'},
        {'>':'&gt;'},
        {'"':'&quot;'},
        {"'":'&apos;'},
        {'`':'&grave;'},
        {'\n':'<br>'},
        {' ':'&nbsp;'}
        ];
    return replaceManyStr(replacements,str);
    } // HTMLToSafeHTML

function replaceManyStr(replacements,str)
    {
    return replacements.reduce((accum,t) => accum.replace(new RegExp(Object.keys(t)[0],'g'),t[Object.keys(t)[0]]),str);
    }

You can just try this :

str.replace(/[.#]/g, 'replacechar');

this will replace .,- and # with your replacechar !

You could also try this :

function replaceStr(str, find, replace) {
    for (var i = 0; i < find.length; i++) {
        str = str.replace(new RegExp(find[i], 'gi'), replace[i]);
    }
    return str;
}

var text = "#here_is_the_one#";
var find = ["#","_"];
var replace = ['',' '];
text = replaceStr(text, find, replace);
console.log(text);

find refers to the text to be found and replace to the text to be replaced with

This will be replacing case insensitive characters. To do otherway just change the Regex flags as required. Eg: for case sensitive replace :

new RegExp(find[i], 'g')