Duplicate Definition in JavaScript.

[dmjpro]

Today i encountered a typical thing. So far what i knew that JavaScript had a scope inside a function but it was not there. I think in newer version of JavaScript it is introduced, in older version there may be. Anyway .....
Have a look at my code snippet ....

function test(){
var s = "Hello!";
var s = "Hi!";
alert(s); //it alerts the latest value of s, and here is no duplicate definition of s
}
 

function test(){
//some code
}
 
function test(){
//some latest code
}
 

Whenever i call test it executes the latest code, here is also not duplicate definition. How JavaScript handles it?
Please explain.

[gits]

with you first example you REdeclare var s within the function ... when you set the javascript-engine to handle the interpretation of the code in strict-mode in firefox/mozilla then the error console will show you that as a warning.

the second is OVERwriting ... basically functions are declared in the window-scope and there you overwrite the first with the second ... basically what you do is:

this.test = function() {
    // some code 
}
 

where this is the window-object's scope ...

kind regards

[rnd me]

scope is only preserved and layered in functions:

function test(){
  function test(){
    return test;
  }
 return test;
}

tests:

test().toString() // =

function test() {
    return test;
}
 

test.toString() // =

function test() {
 
    function test() {
        return test;
    }
 
    return test;
}
 
 

[gits]

ahh ... and to put FF into strict-mode ... type in the address-bar: about:config there a filter appears and you type in the filter: javascript.options.strict ... set its value to true -> see what a bunch of errors and information you now get in the console additionally :)

kind regards