问题描述
我们可以在函数中传递一个不可变作为参数的变量的引用吗？
Can we pass a reference of a variable that is immutable as argument in a function?
示例：
var x = 0;
function a(x)
{
x++;
}
a(x);
alert(x); //Here I want to have 1 instead of 0
推荐答案
由于JavaScript不支持通过引用传递参数，因此您需要将变量改为对象：
Since JavaScript does not support passing parameters by reference, you'll need to make the variable an object instead:
var x = {Value: 0};
function a(obj)
{
obj.Value++;
}
a(x);
document.write(x.Value); //Here i want to have 1 instead of 0在此case， x 是对象的引用。当 x 传递给函数 a 时，该引用被复制到 obj 。因此， obj 和 x 在内存中引用相同的东西。更改 obj 的 Value 属性会影响 Value 属性 x 。
In this case, x is a reference to an object. When x is passed to the function a, that reference is copied over to obj. Thus, obj and x refer to the same thing in memory. Changing the Value property of obj affects the Value property of x.
Javascript将始终按值传递函数参数。这只是语言的规范。你可以在两个函数的本地范围内创建 x ，而不是传递变量。
Javascript will always pass function parameters by value. That's simply a specification of the language. You could create x in a scope local to both functions, and not pass the variable at all.
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