templateSettings not working

Question

I get a compilation error at runtime when I attempt to render the following template:

Answer 1

You have two problems:

1. Your templateSettings regexes overlap in a bad way.
2. Your templateSettings don't match your template.

The documentation isn't explicit about what order the regexes are applied in but the source code is:

var matcher = new RegExp([
  (settings.escape || noMatch).source,
  (settings.interpolate || noMatch).source,
  (settings.evaluate || noMatch).source
].join('|') + '|$', 'g');

In particular, interpolate will be matched before evaluate. Your interpolate is looking for things like {{ ... }} so it will pick up things like {{= ... }} before your evaluate regex can see them. The result will be stray = in the generated source code. So your interpolate regex can't match things that your evaluate will be looking for. You probably want to use these regexes:

_.templateSettings = {
    evaluate: /\{\{(.+?)\}\}/g,
    interpolate: /\{\{=(.+?)\}\}/g,
    escape: /\{\{-(.+?)\}\}/g
};

Note that I've switched who looks for {{= ... }} and {{ ... }}.

Then your template needs to use the Mustache-style delimiters rather than the default Underscore ones:

<script id="tmpl-books" type="text/template">
    {{ _.each(items, function(item) { }}
        <ul>
            <li>Title: {{= item.title }}</li>
            <li>Author: {{= item.author }}</li>
        </ul>
    {{ }); }}
</script>

Fixing those two issues should make things work.

Demo: http://jsfiddle.net/ambiguous/my49N/