unexpected token java что это
Uncaught SyntaxError: Unexpected token — что это означает?
Самая популярная ошибка у новичков.
Когда встречается. Допустим, вы пишете цикл for на JavaScript и вспоминаете, что там нужна переменная цикла, условие и шаг цикла:
for var i = 1; i // какой-то код
>
После запуска в браузере цикл падает с ошибкой:
❌ Uncaught SyntaxError: Unexpected token ‘var’
Что значит. Unexpected token означает, что интерпретатор вашего языка встретил в коде что-то неожиданное. В нашем случае это интерпретатор JavaScript, который не ожидал увидеть в этом месте слово var, поэтому остановил работу.
Причина — скорее всего, вы пропустили что-то из синтаксиса: скобку, кавычку, точку с запятой, запятую, что-то подобное. Может быть, у вас была опечатка в служебном слове и язык его не распознал.
Что делать с ошибкой Uncaught SyntaxError: Unexpected token
Когда интерпретатор не может обработать скрипт и выдаёт ошибку, он обязательно показывает номер строки, где эта ошибка произошла (в нашем случае — в первой же строке):
Если мы нажмём на надпись VM21412:1, то браузер нам сразу покажет строку с ошибкой и подчеркнёт непонятное для себя место:
По этому фрагменту сразу видно, что браузеру не нравится слово var. Что делать теперь:
JavaScript Error Handling: Unexpected Token
Today, as we slice through the choppy seas of our mighty JavaScript Error Handling series, we’re going to smash ourselves against the rocks of the Unexpected Token error. Unexpected Token errors are a subset of SyntaxErrors and, thus, will only appear when attempting to execute code that has an extra (or missing) character in the syntax, different from what JavaScript expects.
Throughout this adventurous article we’ll explore the Unexpected Token error, down to its briny depths, including where it sits within the JavaScript error hierarchy. We’ll also look at how to deal with the many different types of Unexpected Token errors that may occur, depending on the scenario you find yourself in, so let’s get a bit of that wind in our hair and get to it!
The Technical Rundown
When Should You Use It?
Like most programming languages, JavaScript tends to be fairly particular about its syntax and the way it is written. While we don’t have time to cover everything that JavaScript expects (far more information can be found in the official documentation), it’s important to understand the basic premise of how JavaScript parsers work, and therefore what syntax is expected.
Statements in JavaScript are instructions that are concluded with a semicolon ( ; ), while all spaces/tabs/newlines are considered whitespace, just as with most languages. JavaScript code is parsed from left to right, a process in which the parser converts the statements and whitespace into unique elements:
Therefore, when JavaScript parses our code, behind the scenes it’s converting everything into these appropriate characters, then the engine attempts to execute our statements in order. However, in situations where the syntax is wrong (often) due to a typo, we might come across an Unexpected Token error, indicating that the parser thinks there should be another element in a particular place, rather than the token that it found there.
As expected, JavaScript didn’t appreciate this and wasn’t sure how to properly parse it, so we get an Unexpected Token error as a result:
Now, the problem is either one of two things:
By including that extra comma in our method call, JavaScript expects a third argument to be included between that final comma and the closing parenthesis. The lack of that third argument is what causes the Unexpected Token error, and is why JavaScript is none too pleased.
As mentioned earlier, there are many different types of Unexpected Token errors, but rather than cover all the possibilities, we’ll just take a look at one more. The important takeaway is that JavaScript’s parser expects tokens and symbols in a particular order, with relevant values or variables in between. Often, Unexpected Token errors are just due to an accidental typo, but to help avoid these, it is quite beneficial to use a code editor that provides some form of auto-completion. This is particularly useful when forming basic logical blocks or writing out method argument lists, since the editor will often automatically provide the necessary syntax surrounding your code snippet.
For example, to create the following snippet, my code editor tried to fix it for me, so I had to manually remove a brace ( > ) to get the desired result. Here we just have a simple if-else block, but we’re forgotten the closing brace ( > ) prior to the else :
When JavaScript parses this, it expects that brace character, but instead it gets the else :
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Uncaught SyntaxError: Unexpected token :
I am running an AJAX call in my MooTools script, this works fine in Firefox but in Chrome I am getting a Uncaught SyntaxError: Unexpected token : error, I cannot determine why. Commenting out code to determine where the bad code is yields nothing, I am thinking it may be a problem with the JSON being returned. Checking in the console I see the JSON returned is this:
I don’t see any problems with it, why would this error occur?
24 Answers 24
Uncaught SyntaxError: Unexpected token from the server.
This has just happened to me, and the reason was none of the reasons above. I was using the jQuery command getJSON and adding callback=? to use JSONP (as I needed to go cross-domain), and returning the JSON code <"foo":"bar">and getting the error.
This is because I should have included the callback data, something like jQuery17209314005577471107_1335958194322(<"foo":"bar">)
Here is the PHP code I used to achieve this, which degrades if JSON (without a callback) is used:
Hopefully that will help someone in the future.
I have just solved the problem. There was something causing problems with a standard Request call, so this is the code I used instead:
If anyone knows why the standard Request object was giving me problems I would love to know.
I thought I’d add my issue and resolution to the list.
I was getting: Uncaught SyntaxError: Unexpected token and the error was pointing to this line in my ajax success statement:
I later found that in addition to the json results, there was HTML being sent with the response because I had an error in my PHP. When you get an error in PHP you can set it to warn you with huge orange tables and those tables were what was throwing off the JSON.
I found that out by just doing a console.log(response) in order to see what was actually being sent. If it’s an issue with the JSON data, just try to see if you can do a console.log or some other statement that will allow you to see what is sent and what is received.
When you request your JSON file, server returns JavaScript Content-Type header ( text/javascript ) instead of JSON ( application/json ).
Responses with javascript content-type will be evaluated automatically.
In result MooTools tries to evaluate your JSON as JavaScript, and when you try to evaluate such JSON:
as JavaScript, parser treats < and >as a block scope instead of object notation. It is the same as evaluating following «code»:
As you can see, : is totally unexpected there.
It sounds like your response is being evaluated somehow. This gives the same error in Chrome:
This is due to the braces ‘<. >‘ being interpreted by javascript as a code block and not an object literal as one might expect.
I would look at the JSON.decode() function and see if there is an eval in there.
If nothing makes sense, this error can also be caused by PHP Error that is embedded inside html/javascript, such as the one below
Not the
etc in the code that are inserted into html by PHP is causing the error. To fix this kind of error (suppress warning), used this code in the start
To view, right click on page, «view source» and then examine complete html to spot this error.
«Uncaught SyntaxError: Unexpected token» error appearance when your data return wrong json format, in some case, you don’t know you got wrong json format.
please check it with alert(); function
your message received should be: <"firstName":"John", "lastName":"Doe">
and then you can use code below
with out error «Uncaught SyntaxError: Unexpected token»
but if you get wrong json format
ex:
so that you got wrong json format, please fix it before you JSON.decode or JSON.parse
This happened to me today as well. I was using EF and returning an Entity in response to an AJAX call. The virtual properties on my entity was causing a cyclical dependency error that was not being detected on the server. By adding the [ScriptIgnore] attribute on the virtual properties, the problem was fixed.
Instead of using the ScriptIgnore attribute, it would probably be better to just return a DTO.
Uncaught SyntaxError: Unexpected token
I had the same problem and it turned out that the Json returned from the server wasn’t valid Json-P. If you don’t use the call as a crossdomain call use regular Json.
My mistake was forgetting single/double quotation around url in javascript:
Ошибка JSON.parse: Unexpected Token
JSON.parse() выдает ошибку «неожиданный токен» для правильного JSON
Поэтому, чтобы данное исключение не бросалось, необходимо экранировать эти специальные символы, прежде чем передавать строку JSON в функцию JSON.parse.
Вот функция, которая берет строку JSON и экранирует специальные символы:
function escapeSpecialChars(jsonString) <
return jsonString.replace(/\n/g, «\\n»)
.replace(/\r/g, «\\r»)
.replace(/\t/g, «\\t»)
.replace(/\f/g, «\\f»);
>
Таким образом вы можете решить ошибку «unexpected token» при работе с JSON.
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Unexpected token > [closed]
I have a script to open a model window.. Chrome gives me «Uncaught SyntaxError: Unexpected token >» on a line that doesn’t even have a closing curly brace.
Here is the portion of the script that has the error:
Does anybody have any ideas on this? Any help is appreciated.
2 Answers 2
Try running the entire script through jslint. This may help point you at the cause of the error.
Edit Ok, it’s not quite the syntax of the script that’s the problem. At least not in a way that jslint can detect.
Having played with your live code at http://ft2.hostei.com/ft.v1/, it looks like there are syntax errors in the generated code that your script puts into an onclick attribute in the DOM. Most browsers don’t do a very good job of reporting errors in JavaScript run via such things (what is the file and line number of a piece of script in the onclick attribute of a dynamically inserted element?). This is probably why you get a confusing error message in Chrome. The FireFox error message is different, and also doesn’t have a useful line number, although FireBug does show the code which causes the problem.
This snippet of code is taken from your edit function which is in the inline script block of your HTML:
Note that this sets the onclick attribute of an element to invalid JavaScript code:
As an aside, inserting onclick attributes is not a very modern or clean way of adding event handlers in JavaScript. Why are you not using the DOM’s addEventListener to simply hook up a function to the element? If you were using something like jQuery, this would be simpler still.