JavaScript Hoisting Test

javascript-hoisting-test.js

// Ref) http://www.adequatelygood.com/2010/2/JavaScript-Scoping-and-Hoisting

if (typeof print === 'undefined') print = console.log;

var a;

function f() {
    if (0) {
        var a = 456;
    }   
    print(a);
};

function f2() {
    if (0) {
        a = 456;
    }   
    print(a);
}

function f3() {
    if (0) {
        (function(){
            var a = 456;
        })();
    }   
    print(a);
}

function f4() {
    print(a);
    var b = a;
    var a = b;
}

a = 123;
f(); // undefined

a = 123;
f2(); // 123

a = 123;
f3(); // 123

a = 123;
f4(); // undefined

lua.lua

local a                                                                                  

function f() 
    if false then                                                                        
        local a = 456                                                                          
    end
    print(a)                                                                             
end                                                                                      

function f2()
    if false then 
        a = 456                                                                    
    end
    print(a)                                                                             
end                                                                                      

function f3()
    if false then
        (function() 
            local a = 456                                                                
        end)()                                                                           
    end
    print(a)                                                                             
end                                                                                      

function f4()                                                                            
    print(a)
    local b = a                                                                          
    local a = b                                                                          
end                                                                                      

a = 123
f() -- 123                                                                                                                                                                         

a = 123
f2() -- 123                                                                              

a = 123
f3() -- 123                                                                              

a = 123
f4() -- 123

perl.pl

use strict;                                                                                                                                                                        
use warnings;

my $a; 
        
sub f {
    if (0) {
        my $a = 456;
    }
    print "$a\n";
}   
        
sub f2 {
    if (0) {
        $a = 456;
    }       
    print "$a\n";
}   
        
sub f3 {    
    if (0) {
        (sub {
            my $a = 456;
        })->();
    }
    print "$a\n";
}
    
sub f4 {
    print "$a\n";
    my $b = $a;
    my $a = $b;
} 

$a = 123;
f(); # 123

$a = 123;
f2(); # 123

$a = 123;
f3(); # 123

$a = 123;
f4(); # 123

python.py

a = None

def f():
    if 0:
        a = 456 
    print a

def f2():
    global a
    if 0:
        a = 456 
    print a

def f3():
    if 0:
        def _f():
            a = 456 
        _f()
    print a

def f4():
    print a
    b = a 
    a = b 

a = 123 
#f() # UnboundLocalError: local variable 'a' referenced before assignment

a = 123 
f2() # 123

a = 123 
f3() # 123                                                                                                                                                                         

a = 123 
#f4() # UnboundLocalError: local variable 'a' referenced before assignment

ruby.rb

a = nil                                                                                                                                                                            

def f
    if false
        a = 456 
    end
    puts a
end 
    
$global_a = nil
        
def f2
    if false
        $global_a = 456
    end
    puts $global_a
end         
        
def f3
    if false
        def _f()
            a = 456
        end
        _f()
    end
    puts a
end

def f4
    puts a
    b = a
    a = b
end

a = 123 
f() # nil

$global_a = 123
f2() # 123

a = 123
#f3() # undefined local variable or method `a' for main:Object (NameError)

a = 123
#f4() # undefined local variable or method `a' for main:Object (NameError)

Scala.scala

var a = 0;

def f() = { 
    if (false) {
        var a = 456;
    }   
    println(a);
}

def f2() = { 
    if (false) {
        a = 456;                                                                                                                                                                   
    }   
    println(a);
}

def f3() = { 
    if (false) {
        (() => {
            var a = 456;
        })();
    }   
    println(a);
}

def f4() = { 
    println(a);
    var b = a;
    // var a = b; // error: forward reference extends over definition of variable b
}

a = 123;
f(); // 123 

a = 123;
f2(); // 123 

a = 123;
f3(); // 123 

a = 123;
//f4(); // error