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
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