javascript - Why do function parameters in Angularjs contain $?

Question

What is the meaning of writing like this?

Answer 1

The naming of function parameters has nothing to do with the framework. You can understand the meaning of this function using your js syntax knowledge. In addition, I was also confused by this way of writing, so my suggestion is that if there is such a similar code, you can ignore it and find better code to learn

Answer 2

$num is just a parameter naming convention and has no special meaning. $scope is the system function name of angular.js

Answer 3

It is not necessary to add it. You can also change it to num. In many languages, $ is added to represent variables

Answer 4

The beginning of

$ means that this is the parameter provided by angular, and $$ means the internal variable of angular, which is just a naming convention of angular.