The $ is an alias for jQuery which (jQuery) is a Javascript library. Plug-ins are usage of the library in a specific fashion which create specific use of the library and extend its functionality.
A '$' in a variable means nothing special to the interpreter, much like an underscore. From what I've seen, many people using jQuery (which is what your example code looks like to me) tend to prefix variables that contain a jQuery object with a $ so that they are easily identified and not mixed up with, say, integers. The dollar sign function $() in jQuery is a library function that is ...
It is shorthand for jQuery (). Which you can use if you want. jQuery can be ran in compatibility mode if another library is using the $ already. Just use jQuery.noConflict (). $ is pretty commonly used as a selector function in JS. In jQuery the $ function does much more than select things though.
here is a code that is working: the jQuery will treat only the buttons that are of class .cls-hlpb, it will take the id of the button that was clicked and will change it according to the data that comes from the ajax.
When inside a jQuery method’s anonymous callback function, this is a reference to the current DOM element. $ (this) turns this into a jQuery object and exposes jQuery’s methods. A jQuery object is nothing more than a beefed-up array of DOM elements.
$("div.id_100 > select > option[value=" + value + "]").prop("selected",true); Where value is the value you wish to select by. If you need to removed any prior selected values, as would be the case if this is used multiple times you'd need to change it slightly so as to first remove the selected attribute
jquery (E) solution is quite-fast on big tables jquery (E) and querySelectorAll (H) solutions are slowest for small tables getElementByName (G) and querySelectorAll (H) solutions are quite slow for big tables Details I perform two tests for read elements by name (A, B, C, D) and hide that elements (E,F,G,H,I) small table - 3 rows - you can run ...
Advantages: Straight-forward, no dependency on jQuery, easy to understand, no issues with preserving the meaning of this within the body of the loop, no unnecessary overhead of function calls (e.g., in theory faster, though in fact you'd have to have so many elements that the odds are you'd have other problems; details).
Jquery.ajax does not encode POST data for you automatically the way that it does for GET data. Jquery expects your data to be pre-formated to append to the request body to be sent directly across the wire.
