Emberjs Handlebars precompiling

Question

My Emberjs app is running slowly so I wanted to precompile my template to ease the runtime a bit. However I\'m lost on how to proceed. I read http://handlebarsjs.com/precomp

Answer 1

You can precompile in the client's browser, as Thomas Bartelmess stated.

You can also precompile using handlebars via nodejs (taken from my very own Jakefile):

var Handlebars = require('handlebars');
precompile = (function () {
    //Lovingly extracted from Ember's sources.
    var objectCreate = Object.create || function (parent) {
            function F() {}
            F.prototype = parent;
            return new F();
        },
        Compiler = function () {},
        JavaScriptCompiler = function () {};

    Compiler.prototype = objectCreate(Handlebars.Compiler.prototype);
    Compiler.prototype.compiler = Compiler;
    JavaScriptCompiler.prototype = objectCreate(Handlebars.JavaScriptCompiler.prototype);
    JavaScriptCompiler.prototype.compiler = JavaScriptCompiler;
    JavaScriptCompiler.prototype.namespace = "Ember.Handlebars";
    JavaScriptCompiler.prototype.initializeBuffer = function () {
        return "''";
    };
    JavaScriptCompiler.prototype.appendToBuffer = function (string) {
        return "data.buffer.push(" + string + ");";
    };
    Compiler.prototype.mustache = function (mustache) {
        if (mustache.params.length || mustache.hash) {
            return Handlebars.Compiler.prototype.mustache.call(this, mustache);
        } else {
            var id = new Handlebars.AST.IdNode(['_triageMustache']);
            if (!mustache.escaped) {
                mustache.hash = mustache.hash || new Handlebars.AST.HashNode([]);
                mustache.hash.pairs.push(["unescaped", new Handlebars.AST.StringNode("true")]);
            }
            mustache = new Handlebars.AST.MustacheNode([id].concat([mustache.id]), mustache.hash, !mustache.escaped);
            return Handlebars.Compiler.prototype.mustache.call(this, mustache);
        }
    };
    return function precompile(string) {
        var ast = Handlebars.parse(string);
        var options = {
            knownHelpers : {
                action : true,
                unbound : true,
                bindAttr : true,
                template : true,
                view : true,
                _triageMustache : true
            },
            data : true,
            stringParams : true
        };

        var environment = new Compiler().compile(ast, options);
        return new JavaScriptCompiler().compile(environment, options, undefined, true);
    };
}());

strPrecompiledTemplate = item.handlebarsTemplateFolders.map(function (dir) {
    console.info("\tProcessing " + dir);
    return readdirRecursiveSync(dir).map(function (file) {
        console.info("\t\t" + file);
        var content = fs.readFileSync(file, 'utf-8');
        content = Handlebars.precompile(content);
        file = file.replace(/\.[^\.]+$/, '').replace(/^src\//g, '').substr(dir.length).replace(/^\/+/, '');
        // Pay attention: The wrap in Ember.Handlebars.template() is important!
        return "Ember.TEMPLATES['"+file+"'] = Ember.Handlebars.template("+content+");";
    }).join("\r\n");
}).join("\r\n");