In JavaScript, how to create a string on several lines?

There are several ways to create multi-line strings in JavaScript:

With ES6, the simplest option is to use template literals:

var str = `This is a string
on several lines`;

With ES5, new lines can be escaped with \:

var str = 'This is a string \
on several lines';

Google JavaScript Style Guide recommends using string concatenation instead escaping new lines:

var str = 'This is a string ' +
	'on several lines';