Concatenating strings with `if` statements in JavaScript

Question

I\'m attempting to set up a script to concatenate some variables inside a string if they exist, in order to place the appropriate metadata tags into a rendered HTML

Answer 1

I liked the readability of Demian Brecht answer, but I would only change the string for a regex instead, because the replace() function only replaces the first match (see more here: JavaScript .replace only replaces first Match)

var metadata_title = "Hello";
var metadata_author = "Me";
var metadata_date = "2011-09-07";

var template = "\
            \
                \
                \
                \
            \
            \
            \
            ";

var data = template.replace(/#title#/g, metadata_title != undefined ? metadata_title : "")
                   .replace(/#author#/g, metadata_author != undefined ? metadata_author : "")
                   .replace(/#date#/g, metadata_date != undefined ? metadata_date : "");