var have talked about in the previous article, it is the key word js-defined variables.
But in es6, the two newly added keyword, keyword for variable declaration: let and const
Then say about the difference between const and var let's:
First of all that var
Var with the definition of variables, you can re-assignment, when I assigned in a function, after calling the function, while changing the values of local variables.
Next, let say
Not repeat declare a variable with let.
When I re-assignment to the same variable in a function and will not affect variables outside of my function. let is block-level scope.
Finally, const
const define the variable assignment can not be repeated. And, const, and let all have the same block-level scope.
What and when to use const let it?
When we define a variable that does not change with the const
Other times and all of them with a let, eg: for loop