Why Does jQuery Throw an 'Unexpected Token o' Error When Parsing JSON?

jQuery's Unforeseen JSON Parsing: Resolving "Unexpected Token o" Error

When striving to master web development's trifecta of HTML, CSS, and JavaScript, a common challenge arises with JSON data handling. This article explores a peculiar error, "Uncaught SyntaxError: Unexpected token o," encountered during an attempt to load JSON data into a table.

The JavaScript code involved was straightforward:

jQuery.get('wokab.json', function(data) {
    var glacier = JSON.parse(data);
});

The JSON file held simple vocabulary entries:

[
    {
        "english": "bag",
        "kana": "kaban",
        "kanji": "K"
    }
]

However, line 11 consistently threw the error, pointing to the var glacier = JSON.parse(data); line. Removing the JSON file resulted in a 404 error, indicating that the file was being accessed.

Unveiling the Hidden Culprit

Delving into the issue, it was discovered that jQuery's get function guesses the data type. Even without explicitly using getJSON(), jQuery attempted to parse the JSON data. This caused a collision as JSON.parse() was subsequently applied to an object.

Resolution

To resolve this error, it's recommended to explicitly use getJSON(), which returns JSON data as a JavaScript object. Alternatively, you can set dataType: 'json' within the get function parameters to specify the desired data type.

Additional Insights

Aditya Mittal's response provides a comprehensive explanation of the underlying issue and offers valuable insights into jQuery's datatype guessing behavior. By understanding the cause and employing the correct methods, you can navigate JSON data handling with ease.

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