Javascript variable scope

论 Analysis: 是 Whether it is a strong type of language C#, C ++, Java and other languages, or weak types of language such as JavaScript, all variables can be abstracted into two types, namely local variables and global variables.

​​​​​​ Global variables: The entire scope is visible. Local variables: Local visible, exit, is destroyed by GC and recycling space.

 Code analysis:

//局部变量
function PartVary() {
    var n = 10;  //表示局部变量，外部不可访问
}
 
PartVary();
alert(n);//error
<br>
//全局变量
function AllVary() {
     n = 10  //表示全部变量，外部可访问
}
PartVary();
alert(n);//10
<br>
var n = 10;
function AllVary() {
    alert(n);
}
 
AllVary();//10

 Summary:

    ​​ Regarding the visibility of variables, those with low scope can access those with high scope, however, those with high scope cannot access those with high scope. Abstract: parent shields child