Multiline strings in JavaScript

https://github.com/sindresorhus/multiline?unicorns

by mofle • 12 years ago

98 68 12 years ago

PavlovsCat2• 12 years ago

I thank you from the bottom of my heart. This drove me crazy when playing around with WebGL and shaders, because for various reasons I didn't want to put those in separate files.

waynecochran• 12 years ago

Why aren't you just doing this, for example?

        <script id="fragment" type="x-shader">
	precision highp float;
	uniform vec3 glyphColor;
	void main() {
	        gl_FragColor = vec4(glyphColor, 1.0);
	}
	</script>

PavlovsCat2• 12 years ago

Because you can't do that from within javascript, and my HTML was really just a stub to load all the javascript I didn't want to have to otherwise deal with.

abrkn• 12 years ago

Yep, I could use this: http://i.gyazo.com/7826deb9e267f52e1f6b4f1afcfb8c4e.png

martin-adams• 12 years ago

Interesting solution. I usually find this type of problem when doing templating in the client when updating things via Ajax. I either use the DOM to store the template or end up concatenating for smaller things.

Since to preserve these comments in minification requires conscious effort, I wonder if there's an alternative that could convert the comments to regular JS before minification. Obviously you can't just run it in Node as normal doing it this way.

ttty• 12 years ago

The first problem I see, is using any build process which will remove all the comments. Therefore your string will become ''. I wonder how to avoid this.

mofle8• 12 years ago

It's mainly intended for use in Node.js, but I've documented how to use it with a minifier for the front-end: https://github.com/sindresorhus/multiline#minification

criswell• 12 years ago

There's a section on minification here: https://github.com/sindresorhus/multiline#minification

mappum• 12 years ago

That's a really smart hack, I didn't realize comments were included in the output of Function#toString. You could do other cool things, e.g. an annotation for type checking:

  function checkType(f) {
    return function(a) {
      var type = f.toString().match(/\/\/(.*)\n/)[1].trim();
      if(type !== typeof(a)) throw new Error('Invalid type');
      return f(a);
    }
  }
  
  var halve = checkType(function(n) {
    // number
    return n / 2;
  });
  
  halve(4); // returns 2
  halve('string'); // emits error

tlrobinson3• 12 years ago

I didn't realize comments were included in the output of Function#toString

Probably because sometimes they're not, depending on the JavaScript engine (though perhaps all of the major modern browsers do)

mofle8• 12 years ago

The following browsers return comments:

- Latest Chrome

- Firefox >=17

- Safari >=4

- Opera >=9

- Internet Explorer >=6

From: https://github.com/sindresorhus/multiline#compatibility

igl2• 12 years ago

Closure Compiler.

chrishawes• 12 years ago

This is really handy for DFP creative templates. Thank you.

adrusi2• 12 years ago

When I was first really to program I was into hacking javascript to do the crazy things I wanted it to do. I basically did exactly this, albeit with a worse interpolation feature[1]. Don't actually do this please. In the browser, just open up a different <script type="text/plain"> and grab the string from that tag. On the server you can just use a file. Any string that's actually long enough for `["foo", "bar"].join("\n")` to be too cumbersome should be in a separate file, especially if the other way involves a massive hack.

[1] http://zurb.com/forrst/posts/Javascript_native_multi_line_st...

jonpacker• 12 years ago

So you would suggest using external text files to store every SQL/Cypher query that is used in a model-based node app?

adrusi2• 12 years ago

Well, if the query is longer than a 3-4 lines then it's really a program in its own right, and yes, I think it deserves its own file.

igl2• 12 years ago

I think i saw 8 libraries before who abused comments like this.

Edit: Yawn.

wldlyinaccurate2• 12 years ago

Probably worth pointing out that this won't play nice with most minification utilities unless you don't mind leaving all comments in the output.

I think for this reason I still prefer using Array.prototype.join for multiline strings:

    var str = [
        '<!doctype html>',
        '<html>',
            '<body>',
                '<h1>❤ unicorns</h1>',
            '</body>',
        '</html>',
    ].join('');

mofle8• 12 years ago

You can use the `/*@preserve` directive.

See: https://github.com/sindresorhus/multiline#minification

wldlyinaccurate2• 12 years ago

Hey, thanks - that'll teach me for not reading the full page!

gravity13• 12 years ago

You can also

  var str = ' \
      <!doctype html> \
      <html> \
        <body> \
          <h1>❤ unicorns</h1> \
        </body> \
      </html> \
  '

I find it's better than string concat because the trailing \ is just one annoying thing rather than three.

tekacs• 12 years ago

... also this is (presumably) 'joined' at parse time, rather than runtime (and so only once per execution, guaranteed).

jaredmcateer• 12 years ago

6 months later:

    var str = ' \
        <!doctype html> \
        <html> \
          <body> \ 
            <h1>❤ unicorns</h1> \
          </body> \
        </html> \
    '

Help I'm maintaining your code and I get a syntax error

andrey-p• 12 years ago

Ooh I really really like this. Preserving newlines (one of the stated usecases for multiline) is dead easy too.

  var str = [
    //...
  ].join("\n");

tlrobinson3• 12 years ago

FYI, CoffeeScript has multiline strings (and a bunch of other nice things!)

mushishi2• 12 years ago

Sorry but what does this have to do with anything?

tlrobinson3• 12 years ago

If you want niceties like multiline strings, CoffeeScript is a better option than clever hacks like this.

    var str = multiline(function(){/*!@preserve
    multi
    line
    string
    */console.log});

Really?

mofle8• 12 years ago

The next version of JavaScript does too: http://www.2ality.com/2011/09/quasi-literals.html

andrelaszlo• 12 years ago

This snippet does the same thing, mostly:

    var multiline = function(){/*
    foo
    bar
    baz
    */}.toSource().match(/\/\*([\s\S]*)\*\//)[1].trim()

mofle8• 12 years ago

Yeah, pretty much, but in Node we wrap repetitive things in modules, as they're super cheap. Your snippet is also missing some things like indentation stripping, error handling and browser support.

dsego• 12 years ago

Why not a pre-processor?

mofle8• 12 years ago

In Node.js you don't want a compile step. In the browser however that would probably be a better solution indeed.

alextgordon• 12 years ago

Why don't you want a compile step?

aikah• 12 years ago

no compile step needed in nodejs. Most third party languages can hack require so using the transpiled language requires no manual compilation.

evilpie• 12 years ago

Note that ES6 will have template string which can be multiline, but time...

Firefox Nightly currently supports just enough of template strings to give you multiline strings.

Excavator• 12 years ago

Since a couple weeks back templating is also implemented¹, just lacking tagged templates and documentation²³.

1: https://bugzilla.mozilla.org/show_bug.cgi?id=688857#c22

2: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Refe...

3: https://developer.mozilla.org/en-US/docs/Web/JavaScript/ECMA...

teddyh• 12 years ago

Today I learned that in JavaScript, comments are significant and part of the code.

(And people complain about Python having significant whitespace?)

Kiro• 12 years ago

Only significant if you want it to be.

cyphunk• 12 years ago

seriously? you people be nuts

    http://stackoverflow.com/a/15558082/2371924
    var myString = function(){/*
      multi-line
      string
    */}.toString().slice(14,-3)

take this code snippet, throw a package.json and some yaml in and make another npm to Show HN.

coldtea4• 12 years ago

Yeah, only it does several other things do. Like optionally removing indend whitespace.

Did you even read TFA?

ricardobeat• 12 years ago

Be sure to scroll to the bottom for a real-world example, this is very brittle.

jgillich• 12 years ago

I just use ES6 template strings together with the es6ify transform for Browserify. Works in all browsers and very likely performs much better than using Function.prototype.toString.

mattdesl• 12 years ago

Cool hack, but a cleaner solution would be to just use fs.readFileSync if you really want long strings, and let browserify/brfs to inline it for you in the browser.

Using this in a library would be pretty unsafe, given how it's browser-dependent, is prone to issues with minifcation, and could just break with future versions of your JS engine.

VeejayRampay• 12 years ago

In other news, the ubiquitous language of the ubiquitous platform of the information age doesn't support multiline strings. But I guess if we keep throwing enough modules and libraries at it, it'll end up being nice to develop for.

Alternatively wait for ES6 or ES7 to (maybe) solve the problem.

tfb• 12 years ago

Weird... I just just randomly looking at this a few days ago upon a search for "js multiline" when wondering about the common way to spell multiline (multi line vs multi-line vs multiline). I was intrigued by his code though, ultimately in awe of the cleverness and conciseness of it. Very cool hack! Crazy coincidence to see the very code on HN only a few days later.

jasonkostempski2• 12 years ago

Cool hack but not supporting multiline strings is a feature as far as I'm concerned. Everyone seems to agree that HTML shouldn't contain JavaScript, why should JavaScript contain HTML?

biscarch2• 12 years ago

That is actually currently being contested by React and .jsx.

That said, I've seen multiline abused for writing SQL queries as well, which would have been better off being written in a separate .SQL file and `fs.read` into a string with a descriptive var name. (Ignoring that massive SQL strings is a code smell imo).

siculars• 12 years ago

Except if your application generates dynamic queries. And not of the sort where variables in the WHERE clause are dynamically evaluated. Of the sort where the entire structure of your SQL is dynamically driven by user interaction with your application.

eob• 12 years ago

At one point the E4X standard (back in 2007?) enabled a cool multi-line string hack by promoting XML elements to language entities. You could say:

    var htmlFragment = "" + (<r><![CDATA[
    l(a
    
    le
    af
    fa
    
    ll
    
    s)
    one
    l
    
    iness
    
    - e.e. cummings
    ;
    ]]></r>);

And then `htmlFragment` would contain your multi-line string. (The addition with the empty string coerces the <r> element to output its `toString()` value, which happens to be the innerHTML).

This is largely a historical factoid, though. I don't think browsers beyond Mozilla ended up supporting E4X.

Really clever hack with the function's toString method!

tach4n• 12 years ago

Wouldn't something like a Sweet.js macro be better for this? Just have it output a string with '\n\' at the end of lines, or using Array.join() or whatever you like.

robgibbons• 12 years ago

This is a very clever hack. Great use of anonymous functions and toString.

z3t4• 12 years ago

If you do multi line strings you could probably do it in a smarter way. Examples:

appendChild instead of innerHTML .html file instead of html inside a .js file. .css file instead of css inside a .js file.

It can get very messy if you store "data" inside JS. Especially if you store markup or styling in the JS.

Multiline strings in JavaScript

Related Stories