Replace Multiple Characters in a String using JavaScript

# Replace Multiple Characters in a String

Use the replace() method to replace multiple characters in a string, e.g. str.replace(/[._-]/g, ' ').

The first parameter the method takes is a regular expression that can match multiple characters.

The method returns a new string with the matches replaced by the provided replacement.

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const str = 'one.two_three-four';

const result = str.replace(/[._-]/g, ' ');
console.log(result); // 👉️ "one two three four"

The String.replace() method returns a new string with one, some, or all matches of a regular expression replaced with the provided replacement.

The method takes the following parameters:

The first argument we passed to the replace() method is a regular expression.

The forward slashes / / mark the beginning and end of the regex.

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const str = 'one.two_three-four';

const result = str.replace(/[._-]/g, ' ');
console.log(result); // 👉️ "one two three four"

In the first example, we match a dot, an underscore and a hyphen.

You can adjust the regular expression according to your use case by updating the characters between the square brackets and the replacement string.

Here is an example that replaces spaces, question marks and dots with an underscore.

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const str = 'one two?three.four';

const result = str.replace(/[\s?\.]/g, '_');
console.log(result); // 👉️ "one_two_three_four"

The String.replace() method returns a new string with the matches of the pattern replaced. The method doesn't change the original string.

Strings are immutable in JavaScript.

# Replace Multiple Characters in a String using replaceAll

Alternatively, you can use the String.replaceAll() method by chaining multiple calls.

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const str = 'one.two_three-four';

const result = str
  .replaceAll('.', '?')
  .replaceAll('_', '?')
  .replaceAll('-', '?');

console.log(result); // 👉️ "one?two?three?four"

The String.replaceAll() method returns a new string with all matches of a pattern replaced by the provided replacement.

The method takes the following parameters:

You can chain multiple calls to the replaceAll() methods because the method returns the string.

This approach is a bit more verbose than using a regular expression with a character class.

However, it allows us to avoid using a regular expression if we have specific characters we want to replace.

The difference in performance is most likely negligible unless you're working with a string that's tens of thousands of characters long.

# Replace Multiple Characters in a String using a pipe | character

An alternative approach you might see is using a pipe | character, which serves as an or in regular expressions.

Here's an example that replaces each whitespace, underscore or exclamation mark with a question mark.

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const str = 'one two_three!four';
const result = str.replace(/\s|_|!/g, '?');

console.log(result); // 👉️ "one?two?three?four"

The \s special character matches spaces, tabs and newlines.

The pipe | allows us to match either one of the characters in the regex.

Which approach you pick is a matter of personal preference.

I'd go with using a character class [] with the replace() method if the team I'm on is comfortable using regular expressions.

Otherwise, I'd probably chain calls to the replaceAll() method.