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Chrome: Uncaught SyntaxError: Unexpected end of input

When loading my page in Google Chrome, I get a vague error in the console:

Uncaught SyntaxError: Unexpected end of input

I have no idea what is causing it. How would I go about debugging this error?

Checking the response in a network sniffer might give you a clue. My guess is that the Content-length header specifies more bytes than the response contains, or maybe the server somehow sends invalid HTML.
Missing } most the time (javascript). Check the end of your classes and functions. Try just adding another closing } at the end of your script and re-autoformat your code. If there is any strange indentation in your code, then somewhere right before that is most likely the spot where a } has gone missing.
I had this issue when loading JS incorrectly. I loaded it as <script>https://example.com/a.js</script> and it should have been <script src="https://example.com/a.js"></script>
I am getting this error today on Google Sheets. My guess is that one of their JS files is so big that its getting terminated without loading fully. Or one of their app servers has a bug and is closing the http connection before the JS file is fully downloaded.

N
Nae

This particular error is one annoying fact about . In most cases your JavaScript is broken in some way. For example missing a } or something like that.

Example given, this will yield "Unexpected end of input" too:

eval('[{"test": 4}') // notice the missing ]

But the root cause of the problems seems to be that the requested JSON url has a Content-Type of text/html which Chrome apparently tries to parse as HTML, which then results in the unexpected end of input due to the fact that the included image tags are being parsed.

Try setting the Content-Type to text/plain I think it should fix the issues.

Nonetheless, V8 could do a better Job about telling one exactly where the input ended unexpectedly.


ok Thanks alot i removed the json request all together and the error went away i've yet to figure out what exactly is wrong with my json request. i just had no idea where to start debugging. if i may ask how did you determine the root cause
It might not be that obvious. I've gotten this error on minified JS due to it being mangled by the minimizer, whereas the unminified JS was perfectly legal and valid. Unfortunately, Chrome only shows the line where the error occurs, which for minimized JS is usually the entire file...
Not so much where the input ended (cuz that would be at the end). Rather, knowing what was expected would help tons.
Saved my tail. I was getting terribly annoyed by the ambiguity. Thanks.
I had the same error, because I was using JSON.parse(text) and text value was empty string
佚名

Try Firebug for Mozilla - it will show the position of the missing }.

http://getfirebug.com/


Didn't need Firebug. The console in Firefox told me exactly what line and what character was missing
Didn't need firefug either. The firefox console ctrl+shift+i will tell you.
Warning, if the script is minimized to a single enormous line, expect Firefox to hang for several minutes/hours/years.
This is by far the easiest way to track down these syntax errors
my god, thank you. i feel like chrome is so far ahead compared to firefox in terms of developer tooling. its amazing how it fails to get this small thing right though. saved me from a big headache!
C
Community

See my case on another similar question:

In my case, I was trying to parse an empty JSON: JSON.parse(stringifiedJSON); In other words, what happened was the following: JSON.parse("");


Yes I had this one also! You can solve easily by providing "{}" instead of an empty string
I was receiving empty json due to a double forward slash in a URL (ex. localhost:8080//mypath/blagh) and the server was returning an empty response for this.
I came here just to confirm this solution.
H
Hubro

I get this error when I have ommitted a closing brace character (})in JavaScript code. Check that your braces are properly balanced.


D
DroidOS

For the record, for anyone trying to find the various causes for this error. An empty HTML5 data attribute

data-mydata = ''

causes the error too. You should check when the data value is a null string and not include the attribute at all. It goes without saying this is largely relevant to script generated HTML.


Never would have figured this out without you. I was using VideoJS and I copied the html for their video player from their page. It had a data-attribute placeholder you could use but I wasn't. The video wasn't loading and I was getting the error everyone is talking about. After deleting data-setup='{"example_option":true}' Everything worked great.
@user1002379, happy I could help.
B
Blaskovicz

The issue for me was that I was doing $.ajax with dataType: "json" for a POST request that was returning an HTTP 201 (created) and no request body. The fix was to simply remove that key/value.


I started a ajax request (upload) and aborted it before it completed and I got this error.
H
Harfatum

JSHint is good at finding the location of missing brackets or bad syntax.


A
Andrew

Another cause of this error: if your API intentionally responds with no response body, but responds with a 200 OK status code instead of a 204 No Content status code. Some JavaScript libraries may not respond well to unexpected content types when there is no content, so use the correct status code!


H
Hawken MacKay Rives

There will definitely be an open bracket which caused the error.

I'd suggest that you open the page in Firefox, then open Firebug and check the console – it'll show the missing symbol.

Example screenshot:

https://i.stack.imgur.com/uP2eq.png


A
Amir Al

My problem was with Google Chrome cache. I tested this by running my web application on Firefox and I didn't got that error there. So then I decided trying emptying cache of Google Chrome and it worked.


J
Johan Doe

In cases where your JavaScript code is minified to a single line, another cause for this error is using // instead of /**/ for your comments.

Bad (comments out everything after // including the closing } for your function)

function example() { //comment console.log('TEST'); }

Good (confines your comment)

function example() { /* comment */ console.log('TEST'); }

Worked, Plus, you should use \" the-text \" as refers to "the-text" also for casting.
G
George_kane

In my case I was adding javascript dynamicly and using double quotes 2 times in string templates so i changed the second to single quotes and the error was gone. I hope it will help some of the people coming here for the same reason.


using addthis I appended to the url with double string and then changed to single quote and the console error disappeared
j
jtate

Trying to parse an empty JSON can be the cause of this error.

When you receive a response from the server or whatever, check first if it's not empty. For example:

function parseJSON(response) {
    if (response.status === 204 || response.status === 205) {
        return null;
    }
    return response.json();
}

Then you can fetch with:

fetch(url, options).then(parseJSON); 

O
OlehZiniak

I faced similar problem using ui bootstrap directive for angularjs - uib-datepicker, when pressing am/pm toggle.

Error in event handler for (unknown): SyntaxError: Unexpected end of JSON input angular timepicker

Turned out it was because of plugin 'Trans-over' (which translates a word when it is clicked). Maybe my answer will help someone, because I didn't found anything on the internet.


s
safhac

Since it's an async operation the onreadystatechange may happen before the value has loaded in the responseText, try using a window.setTimeout(function () { JSON.parse(xhr.responseText); }, 1000); to see if the error persists? BOL


B
Brick

I had this error and fixed it by adding the guard on readyState and status shown here:

var xhttp = new XMLHttpRequest();
xhttp.onreadystatechange = function() {
    if (this.readyState == 4 && this.status == 200) {
          // Your code here
   }
};

H
Harsha Annareddy

if you got error at Anchor tag,just replace "Onclick" with "href" or "href" with "Onclick"


S
Stefano Populin

Setting the Accept header to application/json in the request worked for me when I faced the same problem.


S
Shahid Islam

In my case, i had low internet speed, when i turn off the other user's internet connection then error has gone, strange


S
Sergey V.

https://i.stack.imgur.com/RQEVs.png