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JS variable hoisting inside closure


By : FuzzyBall
Date : July 30 2020, 03:00 AM
will help you The variable a is already visible, but its value {a:1} is not assigned until the var is reached by the execution. Things are somewhat different for local functions declared with function foo(){...} because the names are bound to the respective functions/closures before the execution starts.
If you call the closure i before assigning a a value you get the problem, however with
code :
(function(){
     function i(){
         console.log(foo());
     }
     i();
     function foo() { return 42; }
})();
(function(){
     function i(){
         console.log(foo());
     }
     i();
     var foo = function(){ return 42; }
})();


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Assign to a variable inside a closure a reference to the closure - does it leak?


By : MaciekProgramista
Date : March 29 2020, 07:55 AM
it should still fix some issue The garbage collector is clever enough to detect such cycle references. So it won't leak.

How do I modify a variable that's defined outside of a closure from inside of a closure?


By : Roman Savchenko
Date : March 29 2020, 07:55 AM
wish help you to fix your issue Exactly as you have done; that's not the problem here. The complete error message shows more detail:
code :
error: cannot borrow `t` as immutable because it is also borrowed as mutable [--explain E0502]
    |>         let mut closure = || {
    |>                           -- mutable borrow occurs here
    |>             t.clear();
    |>             - previous borrow occurs due to use of `t` in closure
...
    |>     println!("{}", t);
    |>                    ^ immutable borrow occurs here
    |> }
    |> - mutable borrow ends here
fn main() {
    let mut t = "foo".to_string();
    println!("> {}", t);
    let not_a_closure = &mut t;
    println!("> {}", t);
}
fn main() {
    let mut t = "foo".to_string();
    println!("> {}", t);

    {
        let mut closure = || {
            t.clear();
        };
        closure();
    }

    println!("> {}", t);
}

Variable hoisting inside IIFE (lazy parsing)


By : Rani Sudhir
Date : March 29 2020, 07:55 AM
Any of those help What you're seeing isn't related to hoisting.
Your first example is quite straightforward:
code :
(function test(){
   var test=123;
   console.log(test)
})()
(function test() {
    test = 123;
    console.log(test);
})();

hoisting & closure - confusion


By : user2053952
Date : March 29 2020, 07:55 AM
seems to work fine Indeed those 2 cases are similar, so what's happening here ?
I think you got a bit fooled by your console. Your console always log something when you execute a command anyways. You can read this post to get better acknowledges about what get returned by your console by default when you do h=1; and var h=1;.

Hoisting inside function having same variable name


By : user3098314
Date : March 29 2020, 07:55 AM
To fix this issue You would be right if the var was called b, but the var a already exists. redeclaring a javascript variable that already exists doesn't do anything. It will not change the value to undefined. Try it.
code :
function hoist(a) {
    var a; // no op, does not change a to  undefined.
    console.log(a);
    a = 10;
}

hoist(18);
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