Difference in var and let

[anki2601]

What is the difference between Var and let?

[stetim94]

actually you should include const as well in this comparison.

let and const where introduced in es6, and they are block scoped:

if (true){
   let blockScope = 'hello world';
   var functionScope = 'hello world';
   console.log(blockScope, functionScope);
}

console.log(functionScope);

logging functionScope outside the if clause goes fine, attempting to log blockScope outside the if clause (go ahead, try it), will result in an error

so a block is anything between {}. So var and let have very different scope

as for constant, they also have block scope, but they constant, once a constant variable is declared, it can’t be re-assigned:

const example = 'this goes fine';
example = 'attempting to re-assign, will result in an error';