website-2018/node_modules/hbs/examples/extend/app.js

// 3rd party
var express = require('express');
var hbs = require('hbs');

var app = express();

// set the view engine to use handlebars
app.set('view engine', 'hbs');
app.set('views', __dirname + '/views');

app.use(express.static(__dirname + '/public'));

var blocks = {};

hbs.registerHelper('extend', function(name, context) {
    var block = blocks[name];
    if (!block) {
        block = blocks[name] = [];
    }

    block.push(context.fn(this)); // for older versions of handlebars, use block.push(context(this));
});

hbs.registerHelper('block', function(name) {
    var val = (blocks[name] || []).join('\n');

    // clear the block
    blocks[name] = [];
    return val;
});

app.get('/', function(req, res){
    res.render('index');
});

app.listen(3000);