JS arguments

Catalog

（1） When the function is called , The browser passes in two implicit parameters at a time ;

（1） Verify that... Exists arguments

（2）arguments.length It can be used to get the length of arguments

(3) It has an attribute called callee

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（1） When the function is called , The browser passes in two implicit parameters at a time ;

1. The context object of the function this
2. The object that encapsulates the argument arguments

（1） Verify that... Exists arguments

    <script>
      function fun() {
        console.log(arguments);
      }
      fun();
    </script>

  So there is ;

- arguments It's a Class array object , It can also manipulate data through indexes , You can also get the length

- When the function is called , All the arguments we pass will be in arguments Kept in
 

Class array object ： Let's verify that it's not an array （ The two methods ）

    <script>
      function fun() {
        console.log(arguments instanceof Array);
        console.log(Array.isArray(arguments));
        // console.log(arguments.length);
      }
      fun();
    </script>

Obviously not an array -------- It's an array of classes  

（2）arguments.length It can be used to get the length of arguments

    <script>
      function fun() {
        console.log(arguments.length);
      }
      fun(" Liu ", " home ", " yi ");
    </script>

- Even if we don't define formal parameters , It can also be done through arguments To use arguments ,
Just more trouble
arguments[0] Represents the first argument
arguments[1] Represents the second argument ........

(3) It has an attribute called callee

This property corresponds to a function object , Is the object of the function that you are currently pointing to

    <script>
      function fun() {
        console.log(arguments.callee == fun);
      }
      fun();
    </script>