How to use the hbs.registerHelper function in hbs

registerHelpers: function() {

		// console.log(hbs.compile);

		// hbs.compile

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

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

		hbs.registerHelper('admin', function(name, context) {

			return true;

		});

	},

const Handlebars = require('hbs');

// inspired by https://stackoverflow.com/questions/22103989/adding-offset-to-index-when-looping-through-items-in-handlebars/39588001#39588001
Handlebars.registerHelper('add', (lvalue, rvalue) => parseInt(lvalue) + parseInt(rvalue));

*/

  app.set('host', process.env.HOST || argv.host);
  app.set('port', process.env.PORT || argv.port);
  app.set('views', path.join(__dirname, 'views'));

  /**
   * View Engine
   */

  app.set('view engine', 'hbs');
  app.set('view options', { layout: 'layout' })
  app.engine('handlebars', hbs.__express);

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

    block.push(context.fn(this));
  });

  hbs.registerHelper('block', function(name) {
    const val = (blocks[name] || []).join('\n');
    // clear the block
    blocks[name] = [];
    return val;
  });

*/ 

    // extend
    hbs.localsAsTemplateData(app);
    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));
    });

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

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

    // 模板引擎
    app.set('view engine', 'hbs');

    if (CONFIG.env.dev) {
        app.set('views', path.join(__dirname, '../frontend/src/tpl/dev'));
        hbs.registerPartials(path.join(__dirname, '../frontend/src/tpl/dev/tpl'));
    } else {
        app.set('views', path.join(__dirname, '../frontend/src/tpl/pro'));
        hbs.registerPartials(path.join(__dirname, '../frontend/src/tpl/pro/tpl'));

app.set('view engine', 'hbs');
  app.set('view options', { layout: 'layout' })
  app.engine('handlebars', hbs.__express);

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

    block.push(context.fn(this));
  });

  hbs.registerHelper('block', function(name) {
    const val = (blocks[name] || []).join('\n');
    // clear the block
    blocks[name] = [];
    return val;
  });


  hbs.registerHelper('select', function(selected, options) {
    return options.fn(this).replace(
      new RegExp(' value=\"' + selected + '\"'), '$& selected="selected"');
  });

  hbs.registerHelper('getProperty', function(attribute, context) {
    return context[attribute];
  });

hbsHelpers.init = () => {
    hbs.registerHelper('link_to', (name, params) => {
        if (typeof params === 'string')
            params = JSON.parse(params);
        
        return router.build(name, params);
    });
};

registerHelpers: function registerHelpers() {
    var we = themeEngine.getWe();

    for (var helperName in we.config.template.helpers) {
       hbs.registerHelper( helperName, require( we.config.template.helpers[helperName] )(we, themeEngine) );
    }
  },

View.prototype.registerHelpers = function registerHelpers(we) {
  for (var helperName in this.configuration.helpers) {
     hbs.registerHelper( helperName, require( this.configuration.helpers[helperName] )(we, this) );
  }
};

files.forEach(function(file) {
    var name = path.basename(helpersDir + file, '.js');
    hbs.registerHelper(name, require(helpersDir + file));
});
module.exports = hbs;

fs.readdirSync(helpersDir).forEach((helper) => {
			const name = helper.replace('.js', '');
			if (name === 'pattern') {
				hbs.registerHelper(name, require(path.join(helpersDir, name)));
			}
		});