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What is the difference between variables VAR A and VAR $ A in JavaScript?




Good day!

more and more often in JS scripts come across the proven variable using the dollar sign, i.e. Instead of a simple ad var a I see Var $ a , and in the following code of appeal to this variable, then so $ a , then so $ (a) . Here, for example, a piece of script:

var forms = function () {
  $ ('. JS_FORM'). Each (Function () {
    VAR $ Form = $ (this),
      $ CustomField = $ Form.find ('[Data-Error]'),
      CustomFieldRulls = {};
    var zindexs = function () {
      SetTimeout (Function () {
        $ ('label.error'). Each (Function (I) {
          $ (this) .css ({'z-index': '50'-i})
      }, 200)

Used both ordinary variables and “variables with a dollar”. I do not understand what is the difference between them? It is just done for convenience, or is it something else from a functional point of view?

Answer 1, Authority 100%

I can not be sure of all 146%, but there is a feeling that the dollar icon here is noted the fact that the value of the variable is obtained using a jQuery selector. While other, ordinary JS variables go without this prefix. In principle, it looks sufficiently logical – JS is a language with dynamic typing, and understand by the name of the variable, which is stored in it, it is not always possible. Therefore, the prefix in the form of a dollar facilitates this understanding.

However, regardless of whether my assumption is true, or not, some new feature announcement “with a dollar” does not carry – in JS it is the same symbol that can be used in identifier names, which is other

Answer 2

not quite so. Based on the latest JQuery specification:

& lt; div id = "selector" & gt; & lt; / div & gt;
 var selector = $ ('# selector');
 var selector = $ ('# selector'). context;
 var $ selector = $ ('# selector');
Window.Onload = Ready;

In the first case, Selector will return [Object Object]

In the second [Object HTMLDocument] (so, for completeness of the picture)

And in the third [object HTMLDIVEEMENT]

Briefly, the third option will work as document.getelementbyid (‘selector’); on pure JS.

And there are already looking there yourself, to whom with what and how to work.

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