Develop Reference

Is it possible to move substrings to a specific location with RegEx?

Background: I used quill.js to get some rich text input. The result I want is quite similar to HTML so I went with the quill.container.firstChild.innerHTML approach instead of actually serializing the data. But when it comes to anchor, instead of
Anchor
I actually want
Anchor{{link:test.html}}
With .replace() method I easily got {{link:test.html}}Anchor</a> but I need to put the link description after the Anchor text. Is there a way to swap {{link:test.html}} with the next </a> so I can get the desired result? There can be multiple anchors in the string, like:
str = 'This is a test. And another one here.'
I would like it to become:
str = 'This is a test{{link:test1.html}}. And another one{{link:test2.html}} here.'

You could also use dom methods. The dom is a better html parser than regex. This is a fairly simple replaceWith
str = 'This is a test. And another one here.'
var div = document.createElement('div');
div.innerHTML = str;
div.querySelectorAll('a').forEach(a=>{
a.replaceWith(`${a.textContent}{{link:${a.getAttribute('href')}}}`)
})
console.log(div.innerHTML)

Yes, you can use capture groups and placeholders in the replacement string, provided it really is in exactly the format you've shown:
const str = 'This is a test. And another one here.';
const result = str.replace(/<a href="([^"]+)">([^<]+)<\/a>/g, "$2{{link:$1}}");
console.log(result);
This is very fragile, which is why famously you don't use regular expressions to parse HTML. For instance, it would fail with this input string:
const str = 'This is a test <span>blah</span>. And another one here.';
...because of the <span>blah</span>.
But if the format is as simple and consistent as you appear to be getting from quill.js, you can apply a regular expression to it.
That said, if you're doing this on a browser or otherwise have a DOM parser available to you, use the DOM as charlietfl demonstrates;

How to add a new line in MySql when user hits 'enter' in textarea? [duplicate]

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.

Shortest code supporting the most common EOL styles \r, \n, \r\n and using HTML5 <br>:
s.replace(/\r?\n|\r/g, '<br>')

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'));
}
}
}

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>';

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'

Change Multi line strings to Single line

Hi I have some text in following format,
683101,
682303,
682302,
682315,
683581,
686667,
682008,
683572,
683573,
682313,
686672,
683545 etc....
Each line break'ed into next line with "Enter". I have nearly 2000 lines of text like this. i want o display the above string to a single line like this.
683101,
682303,
682302,
682315,
683581,
686667,
682008,
683572,
683573,
682313,
686672,
683545,
686672,
683545 etc..
I think there is some tweak options in CSS for doing this. Is there a way in JavaScript to do this? Actually it is not a requirement for me, am just curious to know how it is done.
Edit:
In My text editor it looks like this,
When i try to run it, this is what i get.
Thats why i want to remove the enter, multiline.......

You can use Regular expression to remove all the linebreaks and replace them using space.
str = str.replace(/\n/g, ' ');
Here, \n will match all the line-breaks, and replace them by space

I have a simple way for this. You can do this without extra code. Just write like this -
var str = "12345,\
234234,\
234324,\
234324,\
234324,\
234234";
now just add a slash
Ok, If you don't want to use the above method then use another plan is -
take inside an array and after that use the join method
var str = [12345,
234234,
234324,
234324,
234324,
234234];
str.join(",");
If we are using ES6, Then we have an elegant way to do this using Backtick -
var str = `12345,
234234,
234324,
234324,
234324,
234234`;

Since your data is already comma separated, you can try to add "[" to the beginning and append " ].toString().replace(/\n/g," ") " to the end of your data to get a single line string like this:
[683101,
682303,
682302,
682315,
683581,
686667,
682008,
683572,
683573,
682313,
686672,
683545].toString().replace(/\\n/g," ")
then you get:
"683101,682303,682302,682315,683581,686667,682008,683572,683573,682313,686672,683545"
I hope this helps :)

If all you want is to put those values in one line then, you can set those values as the value of a textarea field. This will allow you to read all those values into a javascript string. Afterward you can apply the regular expression that Tushar suggested.
See the code segment below:
<textarea id="content">
683101,
682303,
682302,
682315,
683581,
686667,
682008,
683572,
683573,
682313,
686672,
683545
</textarea>
Here is the javascript:
var content = $('#content').val();
var content = content.replace(/\n/g, ' ');
console.log(content);

Auto-link URL with javascript Regex

I have a paragraph of text which may contain some links in plain text, or some links which are actually links.
For example:
Posting a link: http://test.com, posting an image <img src="http://test.com/2.jpg" />. Posting an actual A tag: http://test.com/test.html
I need to fish out the unformatted links from this piece of text. So any regular expression that will match the first case, but not the second or third case because they are already well formatted links.
I've managed to fish out all the links with this regex: ((http:|https:)\/\/[a-zA-Z0-9&#=.\/\-?_]+), however, am still having trouble distinguishing between the cases.
This needs to be in javascript so I don't think negative lookbehind is allowed.
Any help would be appreciated.
EDIT: I'm trying to wrap the fished out unformatted links in an a tag.

You can use this regex to get URLs outside of tags:
(?![^<]*>|[^<>]*<\/)((http:|https:)\/\/[a-zA-Z0-9&#=.\/\-?_]+)
See demo
We can shorten it a bit, too, with an i option:
(?![^<]*>|[^<>]*<\/)((https?:)\/\/[a-z0-9&#=.\/\-?_]+)
See another demo
Sample code:
var re = /(?![^<]*>|[^<>]*<\/)((https?:)\/\/[a-z0-9&#=.\/\-?_]+)/gi;
var str = 'Posting a link: http://test.com, posting an image <img src="http://test.com/2.jpg" />. Posting an actual A tag: http://test.com/test.html';
var val = re.exec(str);
document.getElementById("res").innerHTML = "<b>URL Found</b>: " + val[1];
var subst = '$1';
var result = str.replace(re, subst);
document.getElementById("res").innerHTML += "<br><b>Replacement Result</b>: " + result;
<div id="res"/>
Update:
To allow capturing inside specific tags, you can whitelist them like this:
var re = /(?![^<]*>|[^<>]*<\/(?!(?:p|pre)>))((https?:)\/\/[a-z0-9&#=.\/\-?_]+)/gi;

Javascript regex not containing keyword with backslashes

I'm having a problem with a javascript regex that has to comment out all tags inside a script tag. But it can not comment out special first script tag with id "ignorescript".
Here is a sample string to regex:
<script id="ignorescript">
var test = '<script>test<\/script>;
var xxxx = 'x';
</script>
Script tag inside ignorescipt has extra backslash because it is JSON encoded (from PHP).
And here is the final result i have to get:
<script id="ignorescript">
var test = '<!ignore-- <script>test<\/script> ignore-->;
var xxxx = 'x';
</script>
Following example works:
content = content.replace(/(<script>.*<\\\/script>)/g,
"<!--ignore $1 ignore-->");
But I need to check that it does not contain a keyword "ignorescript". If that keyword comes up then I do not want to replace anything. Otherwise add ignore comments to whole script tag So far I have gotten this far:
content = content.replace(/(<script.((?!ignorescript).)*<\/script>)/g,
"<!--ignore $1 ignore-->");
It kinda works, but not the way it supposed to be. I also have one more backslash in ending tag. So I changed it to:
content = content.replace(/(<script.((?!ignorescript).)*<\\\/script>)/g,
"<!--ignore $1 ignore-->");
Not it does not find anything at all.

Got it finally working.
Here is the working regex:
/(<script(?!\sid="ignorescript").*?<\\\/script>)/g