jonaskahn/let-const-js.md

## let-const-js.md

      
    Raw
  

              let-const-js.md
            
          
    Let & const


let and const are the block scoped
A block is a chunk of code bounded by {}. A block lives in curly braces. Anything within curly braces is a block.


Ex1:

let greeter = "hey hi";

if (1) {
    let greeter = "hello";
}
console.log(greeter);

let greeter = "hey hi";

if (1) {
    let hello = "hello";
}
console.log(greeter);
console.log(hello);


let can be updated but not re-declared.
const can't be updated or re-declared


Ex2:

OK

    let greeting = "say Hi";
    greeting = "say Hello instead";
    
NOT OK

    let greeting = "say Hi";
    let greeting = "say Hello instead"; // error: Identifier 'greeting' has already been declared