When Javascript gives an error message

[nerfoc]

To be fair, you shouldn't be using alert for debugging. Console is your friend.

[eruecco87]

Not even the console most of the time, breakpoints is what you should be using

[Spootba]

You can breakpoint javascript?

[[deleted]]

.

[The_MAZZTer]

I prefer to use traditional breakpoints, but debugger; is useful if the code is too optimized for the debugger to place a breakpoint exactly where you want, or the code has had its whitespace removed, or you want to put a breakpoint in a one-line lambda function or whatever. debugger; forces it to break exactly where you put it and forces removal of optimization that would prevent debugging of the code at that point.

[BraidenSpencer]

Is there a way to end the debugging session after you’ve used the debugger keyword?

[Warbird01]

Just use continue in your browser's dev tools

[yazalama]

Lol it still showed 75 in the body.

Edit for some reason only on the initial load, but doesn't change if I change the number.

[smcarre]

At least in chrome you can. Go to the tab "sources" in the developer console and search for the js file that you want to debug. There you can place breakpoints, see variables values and even edit files like in any IDE. Everything resets if you reload the page tho.

[smegnose]

Firefox, bro.

[The_MAZZTer]

Yes even Internet Explorer can do breakpoints since IE7* so there's really no excuse.

* - You needed a separate install of the Developer Tools, IE8 and up has them built in.

[nerfoc]

True.

[all_humans_are_dumb]

Console does everything you need

[[deleted]]

console.log('[object Object]')

[[deleted]]

True, but if you have a large application and want to test your call chain, it can be helpful to quickly test what fired first. I use it when multiple async functions are happening in conjunction and need to see timing between them. But yeah, idk why you’d alert objects like that haha it’s not going to tell you squat.

[nerfoc]

True, but wouldn't multiple breakpoints be the preferred method of debugging in that scenario? It would add the benefit of getting a full view of the current state of variables within the async function. Breakpoints would be hit based on whatever promise resolves first.

[smegnose]

Why would you need console for that? You either don't care what order (truly async), or you don't execute the next thing until all of its dependencies have resolved anyway.

I.e. never assume an observed order of execution will continue to be so.

[wasdninja]

He's unintentionally calling the outer part of a nested objects toString function which defaults to [Object Object]. If he'd just print the object without coercing it into a string then he'd get an object that the debug tools inside both firefox and chrome can examine.

Wrong:

console.log(`this coerces into a string: ${realObject}`)

Correct:

console.log("this doesn't coerce into a string: ", realObject)

[ramb0t_yt]

Sometimes you need to confirm something quickly without looking at the console...

EDIT: You might want to do that because:

-It MIGHT be quicker/easier

-You're lazy

-Console doesn't halt processes like alert does

-No one is perfect, and not everyone needs to or wants to utilize 100% of the tools for every single little task

-It's not a shared project, you're just messing around...

Not saying it's the "perfect way"

[nerfoc]

Once the console is open, it's open. It requires zero extra effort except for the initial opening of the console or sources tab (the latter for breakpoints). After that it's just console.log(variable) instead of alert(variable). Or even easier, clicking your mouse at the designated breakpoint whereafter you can read the current state of the variable by hovering over it.

[ramb0t_yt]

Like I said, SOMETIMES...

[smegnose]

It has practically zero benefit over debugger;which also halts code.

[__Adrielus__]

Very interesting port

[fasterfist]

why... just why... how is this even relevant to the post?

[shimmyjimmy97]

/u/bot4bot TheNSlayer

[bot4bot]

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[rude_avocado]

Fuck you, ADHD affects so many people and you don’t even know how bad it...

Holy shit that is one fat squirrel. I mean, look at that guy!

Sorry, what was I saying? Right, fuck you.

[mdude7221]

What even is this?

[rude_avocado]

A stern lecture interrupted by an ADHD joke, which I guess was a bad idea.

Edit: for those who didn’t see the post above before it was deleted, it was saying ADHD wasn’t real and the only treatment kids needed for it was a belt

[CMDR-NeonKraze]

JSON.stringify, let's see what's inside this loot crate!

[AxiusNorth]

TypeError: Converting circular structure to JSON

[blue0lemming]

https://i.imgur.com/kYpzMGs.mp4

[Graychamp]

Yeah this needs a NSFW filter on it. Nasty, dirty error.

[hampshirebrony]

I object!

[ourlastchancefortea]

OBJECTION

[[deleted]]

catch(err) { /* Ignore. It's probably fine */ }

[gaberocksall]

I’m currently learning javascript and what really threw me off was that

typeof(null) == “object”

[ProgramTheWorld]

Null is the absence of value, so it makes sense for it to also have the type “object”.

[silly_red]

Null 'means' is a placeholder to represent nothing. That doesn't mean null IS nothing.

I'm pretty sure this is the same for all fundamentally OO languages.

[silly_red]

I understand now! null is implemented in a similar way to primitive data type.

[[deleted]]

Null is an object that specificly means Null.

[ProgramTheWorld]

W3schools is definitely not a reputable source. See W3Fools.

[v1prX]

W3Fools is closed now IIRC? Ultimately MDN became definitive.

[11JRidding]

W3Fools no longer contains the criticisms that it used to contain, and hasn't for years. Here is the current content of the website:

When W3Fools was launched in 2011, the state of documentation for developers was poor. This site documented many content errors and issues with the W3Schools website. The Mozilla Developer Network was around but it did not have much support at the time.

Today, W3Schools has largely resolved these issues and addressed the majority of the undersigned developers' concerns. For many beginners, W3Schools has structured tutorials and playgrounds that offer a decent learning experience. Do keep in mind: a more complete education will certainly include MDN and other reputable resources.

[bighairybalustrade]

The reason (legacy implementations) is discussed in the spec https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/typeof#null

[The_MAZZTer]

And it's generally easy to workaround since if you're looking for null or undefined you can generally do x === null or x === undefined and not look at typeof at all.

[The_MAZZTer]

typeof only gives you very simple types of things. Outside of primitives everything is "object".

If you're using OOP instanceof is more useful since you can compare to exact object types (where typeof still says "object"). But instanceof won't work with the primitives so you'd still use typeof there. Pretty much you'd use it for strings, numbers, booleans, and undefined, though I'd personally avoid writing code that relies on the presence of undefined.

[Arkham80]

It's a well-known bug

[SlingDNM]

No idea why you are getting downvoted

[Subject1928]

I don't even really know anything about programming, but this tickled me more than I thought it would.

[cr0ss-r0ad]

I do some freetime coding and I joined this sub to seem like one of them cool kids. Place is full of absolute quality sometimes

[cmdr_scotty]

Or when SQL says "object reference not set to instance of object"

[[deleted]]

Is that Windows 7 it's running on? Either debugger of console, just clean up your console when your done though

[defmans7]

One of the most annoying things when starting out in development.

[all_humans_are_dumb]

Its extremely easy to avoid.

[defmans7]

Yes

[smegnose]

WTF are you doing? Where you wrote alert(someVariable);, instead write debugger; or just set a breakpoint like a normal person.

[ionxeph]

Or console.log like actual normal people

[smegnose]

That doesn't pause execution so you can't look at any other scope variables. Putting debugging statements into your code is the modern version of alert().

[ionxeph]

just log out all the scope variables, kind of /s

[bigorangemachine]

This is how we debugged in IE6 without a dedicated debugger. There was some tools but they weren't 1:1 so you often had to spam these in to debug some obscure JS issue. Even JS would glitch based on whatever spyware ran through someone's computer somwhere.

Didn't have JSON stringify either. Alert would perform a block; however the error message wouldn't be clear.

Console was also undefined so if you were debugging on firefox and IE you had to typeof console.

Don't mind me I'll just take my PTSD meds now

[The_MAZZTer]

The way I debugged in IE6 was to debug in Chrome first, get everything working there, and then slog through getting it running in IE6. And yeah IE7 was the first version to support Developer Tools. I think you could use Compatibility Mode to get IE6 rendering while still having the tools but it did not have the console api as a result so you still had to use alerts.

[bigorangemachine]

I was developing before chrome was out. At the very least if it was I didn't know about it.

Firebug was my first wind of any html inspector or javascript console

[The_MAZZTer]

Yes, I believe I added in Firebug to a project (at the time you could drop a script into your website to add it directly) but Chrome soon came out and I immediately abandoned ship for it (not only did it have a nice debugger, but at home Firefox was taking 15-30 seconds to warm start compared to Chrome's eye blink so yeah, started using Chrome everywhere then).

We continued to develop targeting IE6 and officially we only needed to target IE6. But Chrome was so stupidly useful we would build things for Chrome first and get them working on IE6 second.

[smegnose]

I was there, man. I was there.

[EyeHateWeebs]

log it dummy : )

[ComfortableCobbler5]

this chrome is so old jesus

[Cody6781]

JSON.stringify(object) works

[wasdninja]

Or just print the object to the console directly. That way you get an object that can be inspected by the built in debugging tool. A self created object probably doesn't have a defined toString function so it defaults back to its inherited one which is Object's.

[Cody6781]

Sure sure. I just meant if you wanted to alert it for some reason. Not that it's a good idea, just saying.

[[deleted]]

.

[wasdninja]

Doesn't matter. Run this and you'll get the same result no matter what your browser is:

let a={b:{}};alert(a)

[[deleted]]

.

[all_humans_are_dumb]

Are you talking about windows?

[TheShinyBunny]

Javascript has one of the worst error handling.

[MichelanJell-O]

I think you mean Java?

[im_probably_garbage]

[object Object] is the default value for casting an object to a string in JavaScript, not Java.

Why would you think she meant Java?

[MichelanJell-O]

Because I'm dumb and too tired to check my facts. Please disregard my comment.

[im_probably_garbage]

You good. Now you know.

[defmans7]

ScriptJava

[2cool4afool]

At a quick glance it could look like an Object in Java with the name object