Error message displayed by console when attempting to parse JSON data that is in array

Question

Error message displayed by console when attempting to parse JSON data that is in array

After receiving a simple array as my JSON response:

[35,55]

The Chrome network inspector confirms that it is valid JSON. However, when attempting to parse the xhr.responseText using JSON.parse, I am confronted with the error:

Uncaught SyntaxError: Unexpected token :

I have also experimented with using JSON.stringify and utilizing the array without parsing it in JSON.parse, but unfortunately, JavaScript does not recognize it as an array.

According to JSONLint, the JSON is indeed valid.

At this point, I am unsure of what steps to take next. My goal is to successfully utilize my xhr array as an actual array in JavaScript.

javascript ajax json xmlhttprequest

Answer 1

Answer №1

While working with my application, I encountered this error on two separate occasions. My JSON was quite complex compared to yours. Here are the specific scenarios that caused the issue. Make sure that neither of these matches your situation: a. Due to the complexity of my JSON structure, I often missed using commas and sometimes accidentally used curly braces to define an array. b. I needed to align my JavaScript object with a particular class. However, my JSON had two additional values that did not match the class, causing parsing issues. I hope my experience can be beneficial for you!

Answer 2

While working with my application, I encountered this error on two separate occasions. My JSON was quite complex compared to yours. Here are the specific scenarios that caused the issue. Make sure that neither of these matches your situation: a. Due to the complexity of my JSON structure, I often missed using commas and sometimes accidentally used curly braces to define an array. b. I needed to align my JavaScript object with a particular class. However, my JSON had two additional values that did not match the class, causing parsing issues. I hope my experience can be beneficial for you!

Answer 3

Answer №2

The problem arose because I mistakenly used JSON.parse again on a variable that had already been parsed using JSON.parse, causing an error.

Let me illustrate my mistake with an example:

var currentJSON = JSON.parse(xhr.responseText);
var oldJSON = [];
if (currentJSON) {
    /* perform operations with currentJSON, such as comparing it with oldJSON */
    oldJSON = JSON.parse(currentJSON); /* <- This is where the mistake occurred */
}

Here is the correct approach:

var currentJSON = JSON.parse(xhr.responseText);
var oldJSON = [];
if (currentJSON) {
    /* perform operations with currentJSON, such as comparing it with oldJSON */
    oldJSON = currentJSON; /* <- Removed unnecessary use of JSON.parse() on currentJSON */
}

Answer 4

The problem arose because I mistakenly used JSON.parse again on a variable that had already been parsed using JSON.parse, causing an error.

Let me illustrate my mistake with an example:

var currentJSON = JSON.parse(xhr.responseText);
var oldJSON = [];
if (currentJSON) {
    /* perform operations with currentJSON, such as comparing it with oldJSON */
    oldJSON = JSON.parse(currentJSON); /* <- This is where the mistake occurred */
}

Here is the correct approach:

var currentJSON = JSON.parse(xhr.responseText);
var oldJSON = [];
if (currentJSON) {
    /* perform operations with currentJSON, such as comparing it with oldJSON */
    oldJSON = currentJSON; /* <- Removed unnecessary use of JSON.parse() on currentJSON */
}

Answer 5

Answer №3

It was discovered that the problem stemmed from parsing the JSON data more than once.

Answer 6

It was discovered that the problem stemmed from parsing the JSON data more than once.

Error message displayed by console when attempting to parse JSON data that is in array

Answer №1

Answer №2

Answer №3

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