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janis.rou..

debug a promise

in Using jQuery • 4 years ago

I have some old code I am trying to get to work. The debugger stops where it can't load the user template on the error line below with asterisks. I'm guessing the problem is in the promise. Can I just take out some lines on the promise to force it to work for a demo to make it more straightforward? I don't have any data just a default user in the model. Don't need it to be in a promise. One thing I haven't figured out is this line " if(debug && window.console) " I don't know if debug is on or off. I don't know where that is reference.

_loadTemplateAsync = function(tmpId, type){

var promise = '', ext = '.js';

if(type == 'html') {

ext = '.html';

}

else if(type == 'js') {

ext = '.js';

}

promise = promises[tmpId] || $.get(_template_dir + tmpId + ext).error(function () {

if(debug && window.console) {

console.log('Cannot load the ' + tmpId + ' view.'); ********************************

}

});

promises[tmpId] = promise;

return promise;

};

return {

// Use jQuery to asynchronously load the template.

loadTemplate : function(templateId, templateType, callback){

var tmpId = templateId.replace("#", "");

var promise = _loadTemplateAsync(tmpId, templateType);

promise.done(function(template){

callback.call(this, $(template));

});

}

};

})();

Replies(16)

watusiware

Re: debug a promise

4 years ago

Template? Model? Care to give us some context? I guess you are using some Javascript library or framework. You are leaving us with a lot to guess.

If you don't know if debug is on or not, we certainly don't! It's just a variable in your program.

Ditto "promises". It is apparently referencing some global variable named "promises". It's an array, and it seems there is an entry for each tmpld, whatever that is.

jakecigar

Re: debug a promise

4 years ago

In the old days, we used to use a variable without declaring it. So just declare it, and assign it false.

var debug = false;

JΛ̊KE

jakecigar

Re: Re: debug a promise

4 years ago

Your promises are just Ajax promises that you get from $.get. I assume that at some point your code waits for when the Ajax (promise) is resolved or rejected.

JΛ̊KE

watusiware

Re: debug a promise

4 years ago

If you don't want to use a promise, don't use the return value from $.get.

You can use either a success function passed in the the call to $.get() or else use a .done() function to do something after a successful $.get().

jakecigar

Re: debug a promise

4 years ago

The author of the code did not realize that get requests are normally cached by the browser. None of this code is necessary, but it should not hurt anything.

You could replace it with…

var debug=false,
_loadTemplateAsync = function(tmpId, type){
var ext = type === 'html' ? '.html' : '.js';
return $.get(_template_dir + tmpId + ext).error(function () {
if(debug && window.console) {
console.log('Cannot load the ' + tmpId + ' view.');
}
});
};

JΛ̊KE

janis.rou..

Re: debug a promise

4 years ago

Very sorry, I gave you a function but it was really inside a class. Here is all of it. It isn't really a promise. They didn't have that in 2013 I don't think. I left off the place about caching but I did put in the part about var debug = false but maybe I want debugging on since that didn't solve the problem. Yes it is old code with global variables but I just want it to load the view. It is a Backbone.js solution with Jquery. The part it is sticking on is below this code. This is the code that loads the handlebars template. It's on document load from the index page.

var promises = {};

var TemplateManager = (function(){

// dev location

var _template_dir = 'javascripts/templates/',

// Cache the returned deferred/promise by the id of the template

// so that we can prevent multiple requests for the same template

// from making the ajax call.

// This code is only safe to run synchronously. There exists a

// race condition in this function, when run asynchronously,

// which would nullify the benefit under certain circumstances.

_loadTemplateAsync = function(tmpId, type){

var promise = '', ext = '.js';

if(type == 'html') {

ext = '.html';

}

else if(type == 'js') {

ext = '.js';

}

promise = promises[tmpId] || $.get(_template_dir + tmpId + ext).error(function () {

if(var debug = false && window.console) {

console.log('Cannot load the ' + tmpId + ' view.');

}

});

promises[tmpId] = promise;

return promise;

};

return {

// Use jQuery to asynchronously load the template.

loadTemplate : function(templateId, templateType, callback){

var tmpId = templateId.replace("#", "");

var promise = _loadTemplateAsync(tmpId, templateType);

promise.done(function(template){

callback.call(this, $(template));

});

}

};

})();

------------

This is where the error occurs in the debugger .

promise = promises[tmpId] || $.get(_template_dir + tmpId + ext).error(function () {

if(debug && window.console) {

console.log('Cannot load the ' + tmpId + ' view.'); ********

}

});

promises[tmpId] = promise;

return promise;

};

----

This is the jquery in the index.html

jQuery(document).ready(function () {

app = new Auto.App();

Backbone.history.start();

});

--------

This is the backbone app:

Auto.App = Backbone.Router.extend({

routes : {

"" : "showDashboardMain",

"myprofile" : "showEditProfile"

* view object

dashboardView : {},

signinView : {},

initialize : function () {

this.dashboardView = new Auto.View.Dashboard({

"collection" : AutoDashboard

});

/**

* show the user edit profile

showEditProfile : function () {

this.dashboardView.renderUserAccountView();

showDashboardMain : function () {

this.dashboardView.renderDashboardView(); *************stops here cannot show user profile

// show the user profile

}

});

I wish I knew how to debug it. The Auto.app creates the dashboard but it stops at the route I guess for the user profile? Soemthing like that.

jakecigar

Re: debug a promise

4 years ago

var debug = true;

JΛ̊KE

janis.rou..

Re: Re: debug a promise

4 years ago

sorry about that it wasn't a global var. On the app page there was a switch. maybe leaving it on is best.

var Auto = Auto || {};

Auto.Model = Auto.Model || {};

Auto.Collection = Auto.Collection || {};

Auto.View = Auto.View || {};

// debug mode

var debug = true;

jakecigar

Re: Re: debug a promise

4 years ago

On or off, but it must be declared!

JΛ̊KE

jakecigar

Re: debug a promise

4 years ago

We can’t really debug snippets of code.

Make sure you have the latest versions of everything, and share a link to a demo. We don’t want to search for bugs that were fixed long ago.

JΛ̊KE

janis.rou..

Re: Re: debug a promise

4 years ago

i can put it on code pen or something but do you mean upgrade handlebars and jquery to the most recent version?

jakecigar

Re: Re: debug a promise

4 years ago

Yes.

Putting the code in a codepen would not help. We have to see it cause the error.

JΛ̊KE

jakecigar

Re: debug a promise

4 years ago

You can install ngrok - secure introspectable tunnels to localhost so you share share a demo from your localhost.

These snippets of code are not helping much.

JΛ̊KE

janis.rou..

Re: Re: debug a promise

4 years ago

okay i will

watusiware

Re: debug a promise

4 years ago

Is this code you've been showing your own code? Or is it part of backbone.js?

Ah... I plugged a bit of the code into Google, and it found this.

https://lostechies.com/derickbailey/2012/02/09/asynchronously-load-html-templates-for-backbone-views/

Is this where this code comes from? It looks very similar. (Scroll down to the bottom, the author works through different versions of the code, adding caching, for example.)

Note the author's update at the top of the page. He later decided that it was "a very bad idea".

It does use jQuery promises, BTW.

janis.rou..

Re: Re: debug a promise

4 years ago

this is about 3 or 4 years old code and I did work on it but there was another programmer who did most of it. I didn't know there were promises that long ago.

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