How to cut off string after the first line in the paragraph

Question

I have the string as show below:

XXX:Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur cursus lacus sed
justo faucibus id pellentesque nunc porttitor. Sed venenatis tempor dui, nec mattis dolor
ultrices at. Duis suscipit, dolor sed fringilla interdum, magna libero tempor quam, sed
molestie dui urna sed tellus.

How can I add a restriction and cut the string off at the first line? (using javascript).

The end result I would expect is as follows:

XXX:Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur...

So, you want everything until the second space after the first period? Or something else? — Wesley Murch, Dec 08 '11 at 19:30
How do you know what makes the "first line"? Number of characters? Something else? — Ken White, Dec 08 '11 at 19:31
I want the first line of the paragraph. Cut-off everything after the first line — Zhen, Dec 08 '11 at 19:32
@Zhen "first line" doesn't mean anything. How is your first line restricted? — Alex Turpin, Dec 08 '11 at 19:33
@Zhen: Fix your example then, it doesn't match what you say you want. According to your comment, example should end at `Curabitur cursus lacus sed...` You want to break on the `\n` newline character then? Be specific. — Wesley Murch, Dec 08 '11 at 19:33

score 112 · Accepted Answer · answered Dec 08 '11 at 19:30

112

var firstLine = theString.split('\n')[0];

answered Dec 08 '11 at 19:30

Tomalak

332,285
67
532
628

I'm not sure that it *doesn't*, but intuitively that looks like it wouldn't work for text *wrapped* to the next line; only for explicit new-lines? – David Thomas Dec 08 '11 at 19:32
2

@David Thomas: *"Wrapped"*? What does that mean? Either there is a delimiter in the string or there isn't. – Tomalak Dec 08 '11 at 19:37
If you have text in a paragraph, it flows from one line to the next (I always assumed the name for this was 'wrapping,' but I could be wrong); this text is spread over several lines but has no explicit newline character within it (so far as I'm aware, and that's why I said *I'm not sure...*). Assuming that the paragraph was wrapped, automatically, would your `split('\n')` still work? – David Thomas Dec 08 '11 at 19:41
1

@DavidThomas This only splits on `\n ` characters. – asawyer Dec 08 '11 at 19:43
8

@DavidThomas I *know* what the word "wrapping" means. It just does not relate to JavaScript strings (i.e., it has no meaning *in this context*). Its presentation on the screen is not reflected in a String object, so it is nothing you could "split on". – Tomalak Dec 08 '11 at 20:14
This way you split the whole string on all line-break occurrences and return only the first result. If you have thousands of line breaks it means it would match them all before returning any results. Is there no way to only split once on the first occurrence with the string before the match as result[0] and remaining string as result[1]. – Wilt Mar 27 '14 at 14:49
2

@Wilt Of course there is, if you care for that particular case: `theString.slice(0, theString.indexOf('\n'))` – Tomalak Mar 27 '14 at 15:18
@Tomalak it actually works only half. I need both parts in the result (the one before as well as after the index used for splitting). I looked at splice, but that doesn't support strings :( – Wilt Mar 28 '14 at 10:16
4

You're making it complicated, aren't you? ;) Call slice (or substring) twice. The "do what I mean" API has not been invented yet. – Tomalak Mar 28 '14 at 12:03

Wilt · Answer 2 · 2018-10-10T19:42:56.693

Use the optional limit param for increased performance

Tomalak his answer is correct, but in case you want to really only match the first line it will be useful to pass the optional second limit parameter. Like this you prevent that a long string (with thousands of lines) will be splitted till the end before the first match is returned.

With setting the optional limit to 1 we tell the method to return the result as soon as the first match is found with increased performance as a result.

var firstLine = theString.split('\n', 1)[0];

Read more on the limit param for example here in the MDN docs

score 12 · Answer 3 · answered Dec 08 '11 at 19:32

12

If there are actual line returns, and not just some kind of auto-wrapping, you can do this:

str = str.substr(0, str.indexOf("\n"));

http://jsfiddle.net/f6uBT/

answered Dec 08 '11 at 19:32

Alex Turpin

46,743
23
113
145

That answer should be much more effective then answered one. Of course... one if is missing. :) – Arek Bal Jan 05 '14 at 12:14
4

this returns an empty string if there is no newline in str. Not sure everyone expects that. – Romain Vincent Oct 19 '19 at 14:12
subst seems to be deprecated, one is expected to use slice or substring – Suma Jan 29 '22 at 14:32

score 4 · Answer 4 · answered May 04 '15 at 15:07

4

function getFirstLine(str){
    var breakIndex = str.indexOf("\n");

   // consider that there can be line without a break
    if (breakIndex === -1){
        return str;
    }

    return str.substr(0, breakIndex);
}

getFirstLine('first line\nsecond line'); // first line

getFirstLine('text without line break'); // text without line break

answered May 04 '15 at 15:07

ujeenator

26,384
2
23
28

This solution, as an inline statement: var line = str.indexOf("\n") === -1 ? str : str.substr(0, str.indexOf("\n")); – Kent Butler Jul 18 '19 at 22:19

score 2 · Answer 5 · edited Jun 24 '20 at 01:08

2

You should use this function:

string.split(separator, [limit])

separator - the char to split [". " or \r\n ...] limit - optional, int to limit the max chars

edited Jun 24 '20 at 01:08

David Rawson

20,912
7
88
124

answered Dec 08 '11 at 19:36

Oded BD

2,788
27
30

score 1 · Answer 6 · answered Jan 31 '14 at 19:14

Interesting discussion about "wrapped text"... Maybe it's more of an HTML problem than a javascript problem...

Maybe what you really want is to limit the height of the HTML element, and set "overflow=hidden". Then it will display as much as it can fit in one line, and hide the rest. ( but you will not get the little "..." at the end )

KulaGGin · Answer 7 · 2022-12-08T15:05:40.730

The answers with \n work but they're incomplete and, frankly, buggy. The other options to end the string are: \r and \r\n How long can it take you to figure out that you have the \r in your string and you don't understand why your string doesn't match with some other?

The proper solution here is regex, of course:

let text1 = `This is the first line in text1.\n This is the second line.`
let text2 = `This is the first line in text2.\r This is the second line.`
let text3 = `This is the first line in text3.\r\n This is the second line.`
let text4 = `XXX:Lorem ipsum dolor sit amet, consectetur adipiscing elit. Curabitur cursus lacus sed
justo faucibus id pellentesque nunc porttitor. Sed venenatis tempor dui, nec mattis dolor
ultrices at. Duis suscipit, dolor sed fringilla interdum, magna libero tempor quam, sed
molestie dui urna sed tellus.`

let firstLineInText1 = text1.match(/^.*$/m)[0];
let firstLineInText2 = text2.match(/^.*$/m)[0];
let firstLineInText3 = text3.match(/^.*$/m)[0];
let firstLineInText4 = text4.match(/^.*$/m)[0];

document.querySelector(".paragraph1").innerText = firstLineInText1;
document.querySelector(".paragraph2").innerText = firstLineInText2;
document.querySelector(".paragraph3").innerText = firstLineInText3;
document.querySelector(".paragraph4").innerText = firstLineInText4;

<div>
<p class="paragraph1">
</p>
<p class="paragraph2">
</p>
<p class="paragraph3">
</p>
<p class="paragraph4">
</p>
</div>

asawyer · Answer 8 · 2011-12-08T19:36:34.107

-2

var str = document.getElementsByTagName("div")[0].innerHTML;

var firstLine = function(input,cutlength,appendtext){
    if(input.length<=cutlength)
        return input;
    return input.substr(0,cutlength) + appendtext;
}


alert(firstLine(str,50,"..."));

edit - here's a fiddle link http://jsfiddle.net/a3C86/

edited Dec 08 '11 at 19:36

answered Dec 08 '11 at 19:31

asawyer

17,642
8
59
87

Fyi I did not check for newlines as the questions example doesn't match that pattern. – asawyer Dec 08 '11 at 19:37

How to cut off string after the first line in the paragraph

8 Answers8

Use the optional limit param for increased performance