var str = '' +
"<!doctype html>" +
"<html>" +
" <head>" +
" <title>" + title + "</title>" +
" </head>" +
" <body>" +
" <h1>Hello " + name + ", I'm " + age + " years old. </h1>" +
" </body>" +
"</html>" +
";
<multiline id="multiline-test">
<p>{{a.test}}</p><code>{{b}}</code>
</multiline>
document.body.append(multiline('multiline-test', {a: {test: 'this is test'}, b: 'good job'}))