+ 1
DevTools vs JSON Stringify: Task Chain & Login Flow in Sololearn Playground Environment
Why does logging an object in JavaScript sometimes show [object Object] instead of its content, and how can I properly output a JSON object in a readable format for both the DevTools console and the browser? EDIT: I'm creating a task chain and login flow in JavaScript where I want to clearly contrast the difference between how JavaScript objects appear in DevTools logs (e.g., [object Object]) and how they should be serialized properly using JSON.stringify. However, even when logging dynamic objects, I sometimes still see [object Object], depending on how I pass them into the DOM. My goal is to simulate both the incorrect raw output (like DevTools often shows) and the correct JSON output side-by-side in the DOM. Why do some objects still show up as [object Object] even when I'm sure they were passed dynamically and not hardcoded? Is this due to how .textContent coerces objects, or something deeper? This code adresses the problem: https://sololearn.com/compiler-playground/W4P1UlB3iTX5/?ref=app
11 Respuestas
+ 7
still trying to understand what your code is supposed to do, but in your js tab, line 96 have this:
const devtoolsOutput = [
"Login Success: [object Object]",
"User Profile: [object Object]",
"Task Chain: [object Object], [object Object], [object Object]"
];
is it intentional? these are hard-coded strings, not actual objects...
getting an [object, object] output from js is usually a result of passing unparsed object to something that expects a string input. if you want it properly displayed, you have to pass it through JSON.stringify or a custom parsing function; but in your code, there is no object to stringify...
https://www.freecodecamp.org/news/object-object-in-javascript-meaning-in-js/
+ 4
Browsers may or may not implicitly stringify Javascript objects to JSON strings. This depends on the browser's implementation and perhaps also on the content of the object.
+ 4
JSON.stringify has a "depth" and "indentation" parameter.
Perhaps you could still stringify your objects but overwrite the output function to convert objects (instead of having to write the conversion each time)?
https://sololearn.com/compiler-playground/WIxA5f1vt9aJ/?ref=app
+ 3
by "workaround" you mean other ways than explicitly converting to JSON string?
+ 3
Lisa Very nice idea, thank you for this one 🎩👌✨️
+ 3
Konan
a custom function is best if you know the format of your object.
JSON.stringify is a general purpose function, so it have inherent limitations and vulnerabilities.
https://sololearn.com/compiler-playground/W51JU7dblasg/?ref=app
+ 2
Bob_Li Uhhhhm, yes.
That's why it's tagged as 'Incorrect' - but thanks for answering.
However, further down in the code, inside the logLoginObj function, I am passing real JavaScript objects (e.g., the logged-in user and fetched profile) and displaying both the raw coercion (obj.toString() implicitly via .textContent) and the proper JSON stringified version. So the hardcoded section is a visual simulation; the dynamic section is the real comparison.
So I am trying to ask for other ways to use DevTools in this environment, in short terms.
I'm sorry if this hasn't been too clear here.
Lisa Yes, that's the point -> the rendering behavior can vary between browsers.
But in this case, may issue lie less in browser differences and more in how JavaScript handles implicit coercion.
Specifically, when using .textContent = someObject, the object is implicitly converted to a string, which defaults to [object Object] unless toString() is overridden and JSON.stringify is used.
Anyway workarounds in this environment?
+ 2
I build up this new version with some workarounds I collected:
https://sololearn.com/compiler-playground/W87uNRLKyh35/?ref=app
+ 1
This part of the code "tells" the problem straight away:
```javascript
function logLoginObj(obj, label, isDevTools = true) {
const li = document.createElement('li');
// First, log the raw "[object Object]" (simulating DevTools output)
li.textContent = `DevTools (Raw): ${obj}`; // This will show "[object Object]"
if (isDevTools) {
taskLogDevTools.appendChild(li); // DevTools Output (Incorrect)
}
try {
const correctOutput = JSON.stringify(obj, null, 2);
const correctLi = document.createElement('li');
correctLi.textContent = `Correct JSON Output (${label}):\n${correctOutput}`;
if (!isDevTools) {
taskLogJson.appendChild(correctLi); // JSON Stringify Output (Correct)
}
} catch (error) {
const errorLi = document.createElement('li');
errorLi.textContent = `ERROR: Unable to stringify object. Output: ${obj}`;
```
+ 1
Lisa Yes, I mean to maybe use devTools or other options here, but especially in the SoloLearn-Environment.
I e.g. also tried simply using
```javascript
console.dir(Object)
```
which SoloLearn will still coerce to text, but some environments print a slightly expanded view.
There is also the option to manually walk the object and render key-value pairs like this:
```javascript
function renderObj(obj) {
return Object.entries(obj)
.map(([k,v])=>`${k}: ${v}`)
.join('\n');
}
document.getElementById('out').textContent = renderObj(user);
```
where you could get full control over formatting without JSON here.
I just wanted to know more about best practices for different browser-situations..
+ 1
Bob_Li That's also such a good advice, thanks a lot 🎩👌✨️ (now THAT -> is what I was looking for ;<|} )
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