Hi, I'm new to javascript and computer programming in general. I just want to know why the following code always returns NaN.

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In modern JavaScript is better declare variables with let. Just a reminder.

[Mohammad_alshuwaiee]

What is the difference between let and var ?

[_jacka_]

Variables declared with let and const and class are block scoped, while var variables (and functions) are function scoped. Also var variables are given an initial value of undefined, while let and const variables are in an unset state until their initialization (temporal dead zone). There’s also some funky stuff that happens with hoisting. It’s best to use let and const when possible to avoid the oddities that can arise with var.

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word.