Teammates: JS: Avoid using jquery object multiple times, extract as variable

[amarlearning]

when using a jQuery object multiple times (as is the case here for $(entry)), it is preferable to extract the jQuery object as a variable first (prefixing the variable name with a $ to indicate it is a jQuery object), and then reuse that variable in later calls eg:

Expected:

         const $entry = $(e.target); 
         const courseId = $entry.data('courseid'); 
         const studentEmail = $entry.data('studentemail'); 
         const googleId = $entry.data('googleid'); 

Current:
https://github.com/TEAMMATES/teammates/blob/cb4f03f4071ac4f37e5a1d683e5587508f0a622c/src/main/webapp/dev/js/main/adminSearch.es6#L125-L128

The main difference between declaring entry = e.target, followed by using $(entry) later, and declaring $entry = $(e.target) and reusing $entry would be efficiency (no need to create the same object multiple times in the latter case).

[AlexM9200]

Can I take this?

[amarlearning]

@AlexM9200 I think this is a d.FirstTimer issue. Let's wait for the confirmation from any of our @TEAMMATES/seniordevs

[AlexM9200]

This is the same thing in teammates/src/main/webapp/dev/js/main/instructorFeedbackResultsQuestion.es6.
Should I fix it in this pull request or create a new issue?

    const panelHeading = $(this);
    if ($('#show-stats-checkbox').is(':checked')) {
        $(panelHeading).find('[id^="showStats-"]').val('on');
    } else {
        $(panelHeading).find('[id^="showStats-"]').val('off');
    }

    const displayIcon = $(this).find('.display-icon');
    const formObject = $(this).children('form');
    const panelCollapse = $(this).parent().children('.panel-collapse');

[whipermr5]

The scope of this issue can be widened and similar violations can be fixed in the same PR.