1 const PI=3.1415;
2 console.log(PI);//3.1415
3 
4 PI=3;//Uncaught TypeError: Assignment to constant variable.

1 const WIDTH;//Uncaught SyntaxError: Missing initializer in const declaration

1 if(true){
2   const NAME=‘XG‘
3 }
4 
5 console.log(NAME);//Uncaught ReferenceError: NAME is not defined

1 if(true){
2   console.log(NAME);//Uncaught ReferenceError: NAME is not defined
3   const NAME=‘XG‘;
4 }