multiline

Multiline strings in JavaScript

No more string concatenation or array join!

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

Before

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

After

var str = multiline(function(){/*
<!doctype html>
<html>
	<body>
		<h1>❤ unicorns</h1>
	</body>
</html>
*/});

How

It works by wrapping the text in a block comment, anonymous function, and a function call. The anonymous function is passed into the function call and the contents of the comment extracted.

Even though it's slower than string concat, that shouldn't realistically matter as you can still do 2 million of those a second. Convenience over micro performance always.

Install

$ npm install --save multiline

Usage

Everything after the first newline and before the last will be returned as seen below:

var str = multiline(function(){/*
<!doctype html>
<html>
	<body>
		<h1>❤ unicorns</h1>
	</body>
</html>
*/});

Which outputs:

<!doctype html>
<html>
	<body>
		<h1>❤ unicorns</h1>
	</body>
</html>

Strip indent

You can use multiline.stripIndent() to be able to indent your multiline string without preserving the redundant leading whitespace.

	var str = multiline.stripIndent(function(){/*
			<!doctype html>
			<html>
				<body>
					<h1>❤ unicorns</h1>
				</body>
			</html>
	*/});

Which outputs:

<!doctype html>
<html>
	<body>
		<h1>❤ unicorns</h1>
	</body>
</html>

String substitution

console.log() supports string substitution:

var str = 'unicorns';

console.log(multiline(function(){/*
  I love %s
*/}), str);

//=> I love unicorns

Use cases

CLI help output
Test fixtures
Queries - here an example in Cypher, the query language for Neo4j
CLI welcome message - here in a Yeoman generator

Have one? Let me know.

Experiment

I've also done an experiment where you don't need the anonymous function. It's too fragile and slow to be practical though.

It generates a callstack and extracts the contents of the comment in the function call.

var str = multiline(/*
<!doctype html>
<html>
	<body>
		<h1>❤ unicorns</h1>
	</body>
</html>
*/);

FAQ

But JS already has multiline strings with `\`?

var str = 'foo\
bar';

This is not a multiline string. It's line-continuation. It doesn't preserve newlines, which is the main reason for wanting multiline strings.

You would need to do the following:

var str = 'foo\n\
bar';

But then you could just as well concatenate:

var str = 'foo\n' +
'bar';

Note that ES6 will have real multiline strings.

Browser

While it does work fine in the browser, it's mainly intended for use in Node.js. Use at your own risk.

Install

$ npm install --save multiline

(with Browserify)

$ bower install --save multiline

Compatibility

Latest Chrome
Firefox >=17
Safari >=4
Opera >=9
Internet Explorer >=6

Minification

Even though minifiers strip comments by default there are ways to preserve them:

Uglify: Use /*@preserve instead of /* and enable the comments option
Closure Compiler: Use /*@preserve instead of /*
YUI Compressor: Use /*! instead of /*

You also need to add console.log after the comment so it's not removed as dead-code.

The final result would be:

var str = multiline(function(){/*!@preserve
<!doctype html>
<html>
	<body>
		<h1>❤ unicorns</h1>
	</body>
</html>
*/console.log});

xiaoqqchen / multiline Goto Github PK

multiline's Introduction

multiline

Before

After

How

Install

Usage

Strip indent

String substitution

Use cases

Experiment

FAQ

But JS already has multiline strings with \?

Browser

Install

Compatibility

Minification

License

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But JS already has multiline strings with `\`?