What does $ in js mean?

The $ symbol in JavaScript represents a wildcard character that can match any character or the end of a specific string. Specific applications include: 1. Regular expression line end anchor; 2. Alias ​​for selecting and operating elements in the jQuery library; 3. Alias ​​for custom functions in some frameworks.

$ Meaning in JavaScript

In JavaScript, the $ symbol is a wildcard character, which means it can match any characters (including newlines).

Specific usage:

• Regular expression: $ is usually used as the end-of-line anchor point in regular expressions, indicating regular expressions The expression pattern must match the end of the string. For example:

const re = /a$/;
re.test("apple"); // true
re.test("apples"); // false

• jQuery: The $ symbol is an alias for the jQuery library used to select and manipulate web page elements. For example:

$("p").text("Hello, world!"); // 更改所有 
 元素的文本

• Custom function: In some JavaScript frameworks, the $ symbol can be used as an alias for a custom function, depending on how the framework is implemented. . For example, in Vue.js, the $ symbol represents a Vue instance.

It’s worth noting: The

• $ symbol is not a reserved word in JavaScript, which means it can be reassigned or used other purposes.
• In strict mode, the $ symbol cannot be reassigned in regular expressions.
• In jQuery and other libraries, the usage of the $ symbol may vary depending on the specific API of the library.

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