Javascript Multiline Strings (HEREDOC equivalent) - solution

**kevinn_za** · 07-26-2006 04:24 AM

This is my post from another forum - I've found a way to do multiline strings
in Javascript without having to escape special characters, etc.

Here is the post:

I've seen posts on the Net asking if you can do multiline
strings in Javascript code like you can in PHP with the HEREDOC syntax.

I've seen solutions that do it by putting the text in textarea element but haven't seen any where it's done it code.

Here's my way of doing it in code by using anonymous functions and the /* */ comment tags.

Put your multiline string between the /* */ comment tags in an anonymous function and call the GetMultiLine function to get just your string from the anonymous function. Now you can do multiline strings without having to escape quotes, new lines, etc!

I've been a bit lazy to go figure out the regular expression to
do the "replaces" in one line and optimise the function but I'll do that sometime.

TODO: We could insert {x} in the multiline string where x is a variable/expression and replace that part of the string with the actual value by doing an eval, etc.
This way we could do what we can do in PHP where we can insert variables in strings.

Let me know what yawl think.........

<script>

function GetMultiLine(sStr)
{
var s = sStr;

s = s.replace(/function/, '');
s = s.replace(/\(/, '');
s = s.replace(/\)/, '');
s = s.replace(/\{/, '');
s = s.replace(/\}/, '', -1);
s = s.replace(/\//, '');
s = s.replace(/\*/, '');
s = s.replace(/\//, '', -1);
s = s.replace(/\*/, '', -1);

return s;
}

var f = function() {
/*
the
quick
brown
fox
jumps
over
the lazy dog
*/
};

alert(GetMultiLine(new String(f)));

</script>

**digitil** · 08-07-2007 03:21 PM

this leaves a trailing slash at the end of the string and also causes removal of the first slash if you use HTML in the multiline variable.

I rewrote the function so that you can write HTML from the javascript.
Important:
you have to write the first and last line of the variable function like so:

Code:

function(){

and so:

*/};

each without space and in 1 line.

the result:

**ejohnso9** · 09-13-2007 04:12 PM

This is a neat idea, and lack of multiline string support via some sort of 'heredoc' or other syntax (e.g. Python's triple quote) is really a rather astounding shortcoming in JS given it's close association with HTML. (i.e., I think a hack like this is really needed and could be very useful.)

Unfortunately, this solution appears to be highly non-portable.

Under FireFox 2.0.0.6, such comments appear to be "pre-processed" out. This:

Code:

var f = function(){
    var s = "Hello?";
/*
this is a multi line
string with embedded
newlines of its own
*/};

document.write(new String(f));

Will yield this:

Code:

function () {
    var s = "Hello?";
}

Under IE 7.0, I don't even get that: It will print absolutely nothing.
Can anyone else verify that's what happens on those two browsers?
Anyone understand the reason behind that and have a workaround?

I don't have easy access to older browsers to check prior behavior.

**Desetty** · 05-30-2008 11:52 AM

Right, this solution does not work with Mozilla. But it worked with IE 7. Is there any alternative??

**FilDePantin** · 01-03-2009 08:19 AM

Hi,

Personnellement, je préfère tout simplement utiliser la fonction adhoc du capitaine :

Code:

const monTexteWithReturns="\
Une ligne\n\
Une autre ligne\n\
Encore une ligne\
.";

/* Note : les "\n" sont des retours chariot, of course */

C'est-à-dire que :

Code:

monDiv.innerHTML=monTexteWithReturns.replace(/\n/g,"<br />");
// … affichera :
Une ligne
Une autre ligne
Encore une ligne.

/* Remarquer le "." qui n'était pas à la ligne */

Code:

const monTexteWithoutReturns="\
Ceci \
est \
une \
simple \
Phrase.\
";

// … affichera :

Ceci est une simple Phrase.

Pourquoi faire plus compliqué ?…

Bien à vous,

Fil

**Hack** · 01-05-2009 08:34 AM

In English please.

**SamGoody** · 02-23-2009 01:13 PM

Although I don't speak that foreign language, what FilDePantin was rather straightforward:

In Javascript, if a line ends with a backslash, the next line is viewed as a continuation.

So the following multi-line string will work in any browser:

Code:

var myString = "\
one, \
two, \
three";

Alert(myString);
//alerts "one, two, three"

If you want the browser to display the string in multiple lines, add line breaks to each line:

Code:

var myString = "\
one, \r\n\
two, \r\n\
three";

Alert(myString);
//alerts:
one,
two, 
three

As an aside, it is possible to store the string as text inside a div, which is set to display:none, and when needed a regex can collapse it to a string:

Code:

<div style="display:none" id="myString">
one <br/>
two <br/> 
three 
</div>
<script>
var myString = document.getElementById('myString').innerTEXT.replace('<br />', '');

alert(myString);
//alerts:
one two three
</script>

Hopes that helps the other Americans.

If I got it wrong (again, I am no speaking language he using), feel free to add/correct

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