Why Does `json_encode` Sometimes Return Numbers as Strings, and How Can I Prevent This?

json_encode Strings vs. Numbers

When using the PHP json_encode function, you may encounter an issue where numbers are being encoded as strings. This can lead to unexpected behavior when working with JavaScript, as strings cannot be used for numerical operations.

Understanding the Issue

For instance, if you have an array like this:

array('id' => 3)

json_encode will output the following JSON string:

"{ ["id": "3", ...)

Notice that the id property is wrapped in quotes, indicating a string value. When JavaScript encounters this string, it interprets it as such and any numerical calculations performed on it will fail.

Preventing String Encoding

To address this issue, you can use the JSON_NUMERIC_CHECK flag when calling json_encode. This flag instructs PHP to automatically convert numbers to numerical values before encoding.

$arr = array( 'row_id' => 1, 'name' => 'George' );
echo json_encode( $arr, JSON_NUMERIC_CHECK );

This will output:

{"row_id":1,"name":"George"}

With the JSON_NUMERIC_CHECK flag, the row_id property is now a genuine number, enabling you to perform numerical operations on it in JavaScript without any issues.

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