Javascript Replace

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Michael Zippo 04.11.2021

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The replace () function is used to replace text in a JavaScript string. The replace () function takes two arguments, the substring to replace and the new string that will take its place. Regex (p) can also be used to replace text in a string.

Replacing text in a string is a common operation in any programming language. For example, you might want to remove some symbols from a string to make sure your program is working.

Whatever the reason, knowing how to replace text in a JavaScript string can be useful.

In this guide, we’ll take a look at the replace () JavaScript string function and explore how it can be used to modify text.

JavaScript Replace () Syntax

The JavaScript replace () method searches for a string for a pattern or a regular expression. If such a pattern is found in the string, it is replaced with a specified value. replace () returns a new string. The original string is not changed.

The replace () method takes two arguments:

• The pattern or regular expression to search for replace (); and
• A string that should replace any instance of the pattern specified in the first argument.

Let’s take a look at this syntax:

Our first argument, "Pi", is the pattern whose contents we want to replace. The second argument, "P", is the text we want to replace our template with. So our code replaces "Pi" with "P".

Our code prints " Peter " at JavaScript console . Our output is a new string because strings cannot be edited in JavaScript. They are immutable.

The replace () method is added at the end of our chain. You don’t need to specify the string from which you want to replace the values. Only the pattern that you want to find and the text that should replace instances of that pattern are accepted arguments.

replace () JavaScript example

For example, suppose you want to replace the interesting word by intriguing in a string. How would you do? We could use the replace () method:

Our code returns a new string which is as follows:

In the first line, we declare a JavaScript variable called ourInterestingString . This variable contains the value This string is interesting. On the next line, we replace the word interesting with interesting, using the JavaScript string replace () method.

We can see that the word "interesting" has been changed to "intriguing" in our channel.

JavaScript Replace Multiple Sub-strings

If we want to replace multiple parts of our string, we can do so by concatenating our replace () functions. Chaining means that we place several replace () statements one after the other. Here is an example:

Our code returns the following:

Our code replaces all occurrences of the words" This "," string " and" interesting ", with the words" Our ‚"," code ‚"," amazing! ‚", respectively. It then replaces three words with three more in our string using the replace () function.

JavaScript string replace () using Regex

Regular Expression, or regex (p), defines a search pattern. When trying to find or replace characters in a string, using regular expressions can be helpful. The regexp objects give us more control over our replace () function, which allows us to do more interesting replacements.

Here is an example of using regex to replace the letter and with the letter f:

Our code output is as follows:

Our code first declares the variable ourInterestingString and assigns it the value This string is interesting . Next, our code replaces each e in the entire string with the letter f and the function returns our new string.