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Asked: 2024-09-25T21:51:53+05:30 In:

I’m encountering an issue with the postMessage method in JavaScript, specifically getting an Uncaught DOMException. The error states that the execution of postMessage on the window object has failed due to an object being passed that is not serializable. I’m using this method to communicate between an iframe and its parent window. What are the potential reasons for this problem, and how can I resolve it?

I’ve been diving into using the postMessage method in my JavaScript project, trying to set up communication between an iframe and its parent window. However, I’m hitting a wall with some frustrating errors. Specifically, I’m encountering this pesky Uncaught DOMException that says the execution of postMessage on the window object has failed. The error implies that I’m passing an object that’s not serializable, and honestly, I’m a bit lost on figuring out why.

So here’s the deal: I’ve been trying to send a complex object from the iframe to the parent window, and I thought everything was cool since I was using JSON.stringify to serialize it first. But apparently, that’s not enough. I’ve got one or two functions in the object, and I’m guessing that’s part of the issue. But it’s also possible that I’m including some properties that just can’t be serialized, right?

What really confuses me is that I’ve seen some examples where people are passing around whole objects without a hitch, and I can’t help but wonder if there’s something special about my setup. I’ve double-checked the same-origin policy and it looks good, so I don’t think that’s the culprit, but rather, I suspect it’s the structure of the object itself.

Has anyone else run into this problem? What exactly makes an object non-serializable in this context? And how can I adjust my object or the way I’m trying to send it, so it goes through without throwing those darn exceptions? Any tips or best practices to follow would really save my sanity at this point. I could really use some guidance since it feels like I’m just going in circles trying to fix this! Would love to hear how you tackled similar issues or any insights you have on this. Thanks!

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    2 Answers



    1. postMessage Issues

      postMessage Troubleshooting

      Sounds like you’ve hit a classic snag with postMessage and sending data between your iframe and parent window! It’s super common to run into this stuff, especially when you’re trying to send complex objects.

      So, the deal with postMessage is that it can only send data types that can be serialized. You’re right about JSON.stringify being a step in the right direction, but it won’t handle functions, circular references, or certain types of objects (like DOM elements or custom classes) well. If your object has any functions in it, that’s definitely a no-go for serialization. JavaScript just can’t make a string out of that stuff!

      Even if you think you’ve got everything covered, if there’s a single undetectable function or something like a Map or Set, you’ll hit that DOMException. So, it’s a good idea to strip your object down to just plain data – like strings, numbers, arrays, or booleans.

      Here are some tips to help you out:

      • Go through your object and make sure you’re only including JSON-serializable parts—no functions, no undefined values, and no nested objects that might have strange properties.
      • If you really need to send functions or DOM elements, consider sending just a string identifier or a basic data object that reflects what you need, and then re-build the objects or functions in the receiving window.
      • Always inspect the full structure of your object before submitting it to postMessage. You can use console.log to look at the structure and see if anything looks weird.

      Finally, one other thing to check is your data itself—are you sure everything is what you expect? Sometimes, weird data structures sneak in that you might not notice right away.

      Hope this helps clear things up a bit! Just keep testing different setups with your objects, and you’ll find the magic formula. Good luck!


    2. The issue you’re encountering with the postMessage method is quite common when dealing with complex objects. In JavaScript, objects that are non-serializable typically include functions, DOM nodes, and circular references. Since you mentioned that your object has one or two functions, that’s likely the immediate cause of the Uncaught DOMException you’re seeing. When using JSON.stringify, it converts the object into a JSON string representation, but it does not serialize functions or properties that are not plain data. To resolve this, you’ll need to strip out any functions and ensure that the object only contains serializable data types, such as strings, numbers, and arrays. An alternative approach could be to create a simplified object specifically for the purpose of communication, ensuring that all data fits within the serializable constraints.

      Additionally, consider the possibility of other non-serializable properties in your object. If there are nested objects, make sure they are also free of any functions or non-primitive data types. Moreover, one common error arises from passing circular structures, where an object refers back to itself, intentionally or unintentionally. If your object structure is deeply nested, tools like lodash‘s cloneDeep function can help to make a deep copy before serialization, allowing you to manipulate it and ensure it’s valid for postMessage. Ultimately, keep your communication data as simple as possible. Try debugging by sending smaller chunks of data to see where serialization breaks down, which can clarify which part of the object is causing the issue.

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