How do I replace all line breaks in a string with <br /> elements?

How can I read the line break from a value with JavaScript and replace all the line breaks with <br /> elements?

Example:

A variable passed from PHP as below:

  "This is man.
         
     Man like dog.
     Man like to drink.
    
     Man is the king."

I would like my result to look something like this after the JavaScript converts it:

  "This is man<br /><br />Man like dog.<br />Man like to drink.<br /><br />Man is the king."

This will turn all returns into HTML

str = str.replace(/(?:\r\n|\r|\n)/g, '<br>');

In case you wonder what ?: means. It is called a non-capturing group. It means that group of regex within the parentheses won't be saved in memory to be referenced later. You can check out these threads for more information:
https://stackoverflow.com/a/11530881/5042169 https://stackoverflow.com/a/36524555/5042169

If your concern is just displaying linebreaks, you could do this with CSS.

<div style="white-space: pre-line">Some test
with linebreaks</div>

Jsfiddle: https://jsfiddle.net/5bvtL6do/2/

Note: Pay attention to code formatting and indenting, since white-space: pre-line will display all newlines (except for the last newline after the text, see fiddle).

Without regex:

str = str.split("\n").join("<br />");

This works for input coming from a textarea

str.replace(new RegExp('\r?\n','g'), '<br />');

If the accepted answer isn't working right for you then you might try.

str.replace(new RegExp('\n','g'), '<br />')

It worked for me.

Regardless of the system:

my_multiline_text.replace(/$/mg,'<br>');

It is also important to encode the rest of the text in order to protect from possible script injection attacks

function insertTextWithLineBreaks(text, targetElement) {
    var textWithNormalizedLineBreaks = text.replace('\r\n', '\n');
    var textParts = textWithNormalizedLineBreaks.split('\n');

    for (var i = 0; i < textParts.length; i++) {
        targetElement.appendChild(document.createTextNode(textParts[i]));
        if (i < textParts.length - 1) {
            targetElement.appendChild(document.createElement('br'));
        }
    }
}

Shortest code supporting the most common EOL styles \r, \n, \r\n and using HTML5 <br>:

s.replace(/\r?\n|\r/g, '<br>')

This worked for me when value came from a TextBox:

string.replace(/\n|\r\n|\r/g, '<br/>');

For those of you who just want to allow max. 2 <br> in a row, you can use this:

let text = text.replace(/(\r?\n){2,}/g, '<br><br>');
text = text.replace(/(\r?\n)/g, '<br>');

First line: Search for \n OR \r\n where at least 2 of them are in a row, e.g. \n\n\n\n. Then replace it with 2 br

Second line: Search for all single \r\n or \n and replace them with <br>

if you send the variable from PHP, you can obtain it with this before sending:

$string=nl2br($string);

> It will replace all new line with break

str = str.replace(/\n/g, '<br>')

> If you want to replace all new line with single break line

str = str.replace(/\n*\n/g, '<br>')

> Read more about Regex : https://dl.icewarp.com/online_help/203030104.htm this will help you everytime.

Not answering the specific question, but I am sure this will help someone...

If you have output from PHP that you want to render on a web page using JavaScript (perhaps the result of an Ajax request), and you just want to retain white space and line breaks, consider just enclosing the text inside a <pre></pre> block:

var text_with_line_breaks = retrieve_some_text_from_php();
var element = document.querySelectorAll('#output');
element.innerHTML = '<pre>' + text_with_line_breaks + '</pre>';

Try

let s=`This is man.

     Man like dog.
     Man like to drink.

     Man is the king.`;
     
msg.innerHTML = s.replace(/\n/g,"<br />");

<div id="msg"></div>

I had a config in PHP that was being passed in from the Controller. (Laravel)

Example: PHP Config

'TEXT_MESSAGE' => 'From:Us\nUser: Call (1800) 999-9999\nuserID: %s'

Then in javascript using es6 reduce. notice I had to have two \\ or the output was not being replace correctly. Here are the parameters that are assoicated with the reduce function

• previousValue (the value resulting from the previous call to callbackfn)
• currentValue (the value of the current element)
• currentIndex Optional
• array (the array to traverse) Optional

//p is previousVal
//c is currentVal
String.prototype.newLineReplace = function(){
	return [...arguments].reduce((p,c) => p.replace(/\\n/g,c), this);
}

Here is how i used it in my script.

<script type="text/javascript">var config = @json($config);</script>

config.TEXT_MESSAGE.newLineReplace("<br />")

of course you could just called it on a javascript sring like...

let a = 'From:Us\nUser: Call (1800) 999-9999\nuserID: %s'
var newA = a.newLineReplace("<br />")

//output
'From:Us<br />User: Call (1800) 999-9999<br />userID: %s'

string2 = string2.replace(/(?:\\n)/g, '')