tutorial on JavaScript function parameters and scopes

Function argument Small example one:

FnA (1,2);
FnA (2,3);
function FnA (a,b)
{
alert (A+B);
}

Function argument Small instance one:

Css:
body,ul{margin:0;padding:0;}
li{List-style:none;}
. box{width:200px; margin:20px Auto;
. box ul{height:30px;
Box li{width:50px;height:30px;background: #ccc; color: #000; float:left; text-align:center;line-height:30px; font-size:20px;}
#box1. Active1{background: #333; color: #fff;}
#box2. Active2{background: #666; color:red;}
. content{height:60px;border:1px solid #ccc;}
. Content div{display:none;font-size:50px;
. content. show{Display:block;
Js:
Window.onload=function ()
{
tab ("Box1", "active1");
tab ("Box2", "active2");
};
Function tab (SID,SCLASSNAME)
{
var Obox=document.getelementbyid (sId);
var ali=obox.getelementsbytagname ("ul") [0].getelementsbytagname ("Li");
var adiv=obox.getelementsbytagname ("div") [0].getelementsbytagname ("div");
for (Var i=0;i<ali.length;i++)
{
Ali[i].index=i;
Ali[i].onmouseover=function ()
{
for (Var i=0;i<ali.length;i++)
{
Ali[i].classname= "";
Adiv[i].classname= "";
}
This.classname=sclassname;
Adiv[this.index].classname= "Show";
};
}
}
Html:
<div class= "box" id= "Box1" >
<ul>
<li class= "Active1" >1</li>
<li>2</li>
<li>3</li>
<li>4</li>
</ul>
<div class= "Content" >
<div class= "Show" >1</div>
<div>2</div>
<div>3</div>
<div>4</div>
</div>
</div>
<div class= "box" id= "Box2" >
<ul>
<li class= "Active2" >1</li>
<li>2</li>
<li>3</li>
<li>4</li>
</ul>
<div class= "Content" >
<div class= "Show" >1</div>
<div>2</div>
<div>3</div>
<div>4</div>
</div>
</div>
Scope Small Example One:
function Fnaa ()
{
var b=0;
}
function FnBB ()
{
Alert (b)
}
FnBB (); The result is: b is undefined;

A variable defined within a function is called a local variable scope and is only valid within the function
Scope Small Example Two:
var b=0;
function FnBB ()
{
B-=1;
}
FnBB (); -1
FnBB (); -2
alert (b); So-2

Globally defined variables, called global variables, are global in scope and can be modified and used in the global context.
Scope Small Example Three:
function Fnaa ()
{
var a=0;
function FnBB ()
{
var b=0;
alert (a);
}
FnBB ();
}
Fnaa ();

A variable defined within a function is called a local variable scope and is only valid within the function

Globally defined variables, called global variables, are global in scope and can be modified and used in the global context.

function is a scoping problem

The closed Bun function can use the parent function's local variables but the parent function cannot access the contents of the child elements inside