In Vue.js, the meaning of the dollar sign ($) prefix refers to the internal properties or methods of the Vue instance. These properties and methods are used internally by the Vue.js framework, and it is generally not recommended to access or modify them directly. The dollar sign prefix is to distinguish the internal properties and methods of the Vue instance from the user-defined properties and methods.

Question

In Vue.js, what does the dollar sign prefix in front of a property name mean? For example: this.$emit('clicked','demo')

P粉833546953 · Answer

In Vue, an explanation of using the $ and _ prefixes can be found here:

Details are explained in the section.

_For private instance properties:

$ is used for public instance properties:

Both are used to avoid conflicts with property names chosen by the component creator, such as props and data properties.

The

$ prefix is not only used by Vue’s core API. It is also commonly used in libraries that add properties to components. For example:

These are officially supported libraries, but so are many third-party libraries.

It can also be used by application code to create global properties. A common example is adding

$http to Vue.prototype (or globalProperties in Vue 3).

In all these cases,

$ serves as an indicator to future developers that the property is defined elsewhere, not inside the current component.