What is the meaning of sign in JavaScript

Question

A dollar ($) symbol appears in the JavaScript code below. What does it imply?

$(window).bind('load', function() {
    $('img.protect').protectImage();
});

Answer 1

Your code appears to be referencing methods from one of the major JavaScript libraries (jQuery, Prototype, mooTools, and so on).

The usage of $ in JavaScript is not at all strange. $ is just a JavaScript identifier.

JavaScript supports upper and lower case letters, numerals, and the symbols $. The $ was designed to be used for machine-generated variables (for example, $0001).

The $ is the fundamental basic object of Prototype, jQuery, and most Javascript libraries (or function). Most of them also include a method for releasing the $ so that it may be used with another library that supports it. In such a situation, jQuery is used instead of $. In reality, $ is only a shorthand for jQuery.