JS judge the data types object.prototype.tostring.call and typeof

Take a little note ~

Object.prototype.toString.call and typeof Both are used to judge the data type , The former is more specific to judge the data type , What is returned is string or array , The latter is just a return type .

When we use typeof When judging the data type , It is difficult to distinguish and compare two data types . such as ： Use typeof Detection array or null The data types returned during are object, But use Object.prototype.toString.call You can distinguish which is an array , Which number null.

In a nutshell Object.prototype.toString.call You can return data types more specifically .

      console.log(Object.prototype.toString.call("aaa")); // [object String]
      console.log(typeof "aaa"); //string
      
      console.log(Object.prototype.toString.call([123])); // [object Array]
      console.log(typeof [123]); // object
      console.log(toString.call(null)); //[object Null]
      console.log(typeof null); // object

     function a() {
    
        console.log(" function ");
      }
      console.log(Object.prototype.toString.call(a)); // [object Function]
      console.log(typeof a); // function