从函数更新全局变量 [英] Updating a global variable from a function
问题描述
函数计算一个随机数并将其存储在mynumber变量中。
var mynumber;
函数one(){
var mynumber = Math.floor(Math.random()* 6)+ 1;
}
我需要在一个单独的函数中使用它,如下所示。但一个错误表示未定义 - 这意味着函数1的值不会更新。
函数two(){
告警(mynumber的);
}
如何解决这个问题。有没有办法更新mynumber全局变量。
如果用 var
它会在当前范围内创建它。如果你不这样做,它会在全局范围内声明它。
var mynumber;
函数one(){
mynumber = Math.floor(Math.random()* 6)+ 1; //影响全球范围
}
您也可以指定您希望全局范围即使您也定义了一个局部变量:
function one(){
var mynumber = 1; // local
window.mynumber = Math.floor(Math.random()* 6)+ 1; //影响全球范围
}
知道全局范围是 window 你可以通过修改全局变量来获得相当高的技巧:
function one(){
var mynumber = Math.floor(Math.random()* 6)+ 1; // local
window ['mynumber'+ mynumber] = mynumber; //设置window.mynumber5 = 5(或者任何随机结果为)
}
There is a global variable called numbers. Function one calculates a random number and stores it in mynumber variable.
var mynumber;
function one (){
var mynumber = Math.floor(Math.random() * 6) + 1;
}
I need to use it in a separate function as belows. But an error says undefined - that means the value from function one is not updated.
function two (){
alert(mynumber);
}
How to overcome this problem. Is there a way to update the mynumber global variable.
If you declare a variable with var
it creates it inside your current scope. If you don't, it'll declare it in the global scope.
var mynumber;
function one (){
mynumber = Math.floor(Math.random() * 6) + 1; // affects the global scope
}
You can also specify that you want the global scope even if you define a local variable too:
function one (){
var mynumber = 1; // local
window.mynumber = Math.floor(Math.random() * 6) + 1; // affects the global scope
}
Knowing that the global scope is window
you can get pretty tricksy with modifying global variables:
function one (){
var mynumber = Math.floor(Math.random() * 6) + 1; // local
window['mynumber'+mynumber] = mynumber; // sets window.mynumber5 = 5 (or whatever the random ends up as)
}
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