Minimal template processor in JS.

tpl.js

var template = function(ctx, tpl) {
    var accum = [], idx = 0;

    while (true) {
        var start = tpl.indexOf('{{', idx);
        if (start < 0) break;
        var end = tpl.indexOf('}}', start);
        if (end < 0) break;
        
        var str = tpl.slice(start+2, end);
        str = str.replace(/(^\s+|\s+$)/g, '');
        accum.push(tpl.slice(idx, start));

        var r = ctx, path = str.split('.');
        while (path.length > 0 && r !== undefined)
            r = r[path.shift()];
        if (r === undefined) r = '';

        accum.push(r);
        idx = end + 2;
    }

    accum.push(tpl.slice(idx));

    return accum.join('');
}

This is less a templating language than an interpolation engine like sprintf. Example use:

context = { name: 'Brendan', day: new Date() };
template(context, 'Hello {{ name }}, good {{ day }} to you.');

"Hello Brendan, good Fri Jul 08 2011 11:40:08 GMT-0300 (ADT) to you."