Variables and scopes

Tag: statement variable does not function alert TCO if statement pass code

One, var box= "Blue";
function SetColor () {
return 123;
}
alert (box); ==alert (Window.box); ---blue//global variable belongs to window property
Alert (SetColor ()); ==alert (Window.setcolor ()); ---123//The method that the global function belongs to window

Second, var box= "Blue";
function SetColor () {
var box= "Red";
}
SetColor ();
alert (box);---blue//Because the SetColor function is the method under the window Global action, the alert is also a global variable.

var box= "Blue";
function SetColor () {
box= "Red"; The Var is removed, and the variable is a global variable.
}
SetColor ();
alert (box);---red

Third, var box= "Blue";
function SetColor (box) {
Alert (box),----red//parameter is also a local variable
}
SetColor ("Red");
alert (box);---Blue

Four, the scope chain, the function body also contains a function, only this function can access the inner layer of the function.

function Setbox () {

function SetColor () {
return 123;
}
}
Alert (SetColor ()); The error occurs because the SetColor () method is scoped to Setbox () and not within a window. So how to call SetColor:
function Setbox () {

function SetColor () {
return 123;
}
return SetColor ();
}
Alert (Setbox ()); that's it.

But code blocks such as curly braces for an If statement do not have scope functionality, which means that they can be accessed globally through window.

Variables and scopes