Before ES6 (ES2015) there was only one way to declare variables and constants in JavaScript, which was using var.
But var was the cause of some var-y (😅) pesky bugs and strange behaviour due, often, to scoping issues.
Below we have a forLoop inside a function count() that uses var
You'll notice that we can access the value of i inside and outside of the forLoop...
👉 Call the function count() and run node let_vs_var.js to see what gets printed to the console!
...
Well, that's interesting! 😯
As you can imagine, this isn't the behaviour that we want...
Another problem with var is that we can overwrite it.
This might not seem like a big deal... but in a massive code base - overwriting variables without realising is a big issue 🙈
👉 Replace all the vars in this file with let so we get the behaviour we expect!
You should now get some helpful console Errors from JavaScript warning us that i is not defined, and greeting has already been declared.
Sweet!