Is JSlint right and why?

Question

JavaScript

I decided to check my project with jslint (I hadn't used linters before).
Download jslint addin in VScode. All default settings.
I have this code (simplified):

if(true){
var newItem = 10;
}
else{
var  newItem = 20;
}

linter says to do this:

var newItem;
if(true){
newItem = 10;
}
else{
newItem = 20;
}

Please explain why the second option is considered correct?

Answer 1

Replace with let and see if your construct works.
In general, variables should be declared at the beginning of the function.
Also read about raising var. Two vars are simply meaningless.