Parameters of arguments in javascript Functions

At noon, I studied arguments in javascript Functions.
Copy codeThe Code is as follows:
<Script type = "text/javascript">
Window. onload = function (){
(Function (arg1, arg2 ){
Alert (arguments. length );
Alert (arguments. callee. length );
})();
}
</Script>

The arguments. length and arguments. callee are observed.

First, arguments makes sense only in the function body. arguments. length returns the number of arguments passed into the function. For example, if an anonymous function is directly run without being passed in, the first alert must be '0', and then let's look at arguments. callee returns the called function itself. For anonymous functions, you can use arguments. callee gets its reference. Here arguments. callee. length returns the number of parameters that the function is expected to pass in. In this case, the second alert is '2'. If this is a function with a name, such as the function named mytest, you can directly use mytest. length to get the number of parameters that should be passed in.