My code looks like this:

1. Do I need to somehow close the connection? It looks like send() automatically closes the connection because I cannot execute send() twice.

2. Is the error handling ok? When my internet connection was a bit unstable, I got the message "Error: 0". Zero sounds like a strange status code.

Note: For now, I'd like to stick with plain JavaScript, without jQuery or other frameworks.

Thank you very much.

UPDATE: Explanation/Context of the code:

The HTML page has a table. Each table row  represents a dataset with an ID. The id of each row is "line" plus the dataset ID, e.g. "line1". Each table row has a link named "Solve" which calls the JavaScript function _solve(id)  .

1. Do I need to somehow close the connection? It looks like send() automatically closes the connection because I cannot execute send() twice.

2. Is the error handling ok? When my internet connection was a bit unstable, I got the message "Error: 0". Zero sounds like a strange status code.

Note: For now, I'd like to stick with plain JavaScript, without jQuery or other frameworks.

Explanation/context of the code:

The HTML page has a table. Each table row  represents a dataset with an ID. The id of each row is "line" plus the dataset ID, e.g. "line1". Each table row has a link named "Solve" which calls the JavaScript function _solve(id).

Today I created my first simple AJAX application. It works fine, but I am a bit unsure if I did everything correct.

UPDATE: Explanation of the code:

Today I created my first simple AJAX application. It works fine, but I am a bit unsure if I did everything correct. I'd like to use the code as template for future projects.

UPDATE: Explanation/Context of the code:

UPDATE: Explanation of the code:

The HTML page has a table. Each table row  represents a dataset with an ID. The id of each row is "line" plus the dataset ID, e.g. "line1". Each table row has a link named "Solve" which calls the JavaScript function _solve(id) .

<tr id="line61087">   <td>php/error.log</td>   <td><a href="javascript:_solve(61087)">Solve</a></td>   <td>1113</td>   <td>2017-09-03&nbsp;01:18:18</td>   <td>Xyz...</td> </tr> 

When the user clicks at "Solve", a PHP script (ajax_cmd.php) is called with AJAX. The PHP script deletes the dataset and confirms the deletion with the JSON object success: true; id: (the ID) on success or success: false; error: (the error message) on failure.

After the PHP script confirmed the successful deletion, the AJAX script hides the table row and decreases a row counter.

A double-click prevention (which might result in a double-decrease of the counter) is realized with a check if the row is already hidden.