My notes about const, var, and let. Not a guide. Just notes.
Var #
var myName = 'Yasin';
console.log(myName);
You will see Yasin output in console.
var myName = 'Yasin';
myName = 'Dmitry';
console.log(myName);
You will see Dmitry output in console because we changed value of the variable.
var myName = 'Yasin';
var myName = 'Dmitry';
console.log(myName);
You will see Dmitry output in console because. You can redeclarate.
var myName = 'Yasin';
function logMyName() {
console.log(myName);
};
logMyName();
In this example you will see Yasin output in console. You can reach variable even you in a scope.
var myName = 'Yasin';
function logMyName() {
var myName = 'Dmitry';
console.log(myName);
};
logMyName();
In this example you will see Dmitry output in console. You can reach variable in a scope and change it value.
Let #
let myName = 'Yasin';
let myName = 'Dmitry';
console.log(myName);
Redeclaration is not possible. This will throw an error.
Const #
const myName = 'Yasin';
myName = 'Dmitry';
console.log(myName);
Can't change the value of the const. This will throw an error.