It was my understanding that variables created with let in Javascript cannot be global. I thought that meant that the variable only lived in that particular file.
However, when I make a simple/contrived example:
A.js:
let a = 5;
B.js:
console.log(a);
index.html:
<script type="text/javascript" src="A.js"></script>
<script type="text/javascript" src="B.js"></script>
it logs 5! Strangely though if I log window.a, that logs as undefined, so a global variable is not being created.
My question is, how is the variable getting shared between files without being a global variable?
It stays inside the current scope, the most outer block scope (or global scope as Bergi so nicely mentions), so this would work
<script>
let world = 'world';
</script>
<script>
console.log( `hello ${world}` );
</script>Where as this would not
<script>
{
let world = 'world';
}
</script>
<script>
console.log( `hello ${world}` );
</script>it really doesn't matter that you are using 2 different files. In the end, all the scripts that get loaded get put behind each other, optimized and executed
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