Strange behaviour whith shadowing

Question

Although shadowing should never be used (or just to obfuscate) because it's confusing, I wanted to completely understand it. And I got this strange thing :

alert(parseInt('123'));//Here, I expected 123 but it's 'overshadowed'
function parseInt(){return 'overshadowed';}
alert(parseInt('123'));//Here it's 'overshadowed' too

Why the first alert output 'overshadowed' whereas the function is not modified yet?

P.S : I got inspired by Variable shadowing in JavaScript

Answer 1

In JavaScript, all declarations are implicitly placed at the beginning of the scope ("hoisted"), so it doesn't matter if the parseInt() definition was at the second, last, or first line.