Possible Duplicate:
How do JavaScript closures work?
Javascript closures and side effects in plain English? (separately)
我是 JavaScript 新手,但我对闭包的工作原理感到非常困惑。有人可以通俗地解释一下它们是什么或者为什么它们有用吗?
最佳答案
闭包类似于函数定义时的上下文。每当定义函数时,都会存储上下文,即使函数的“正常”生命周期结束,如果您保留对函数执行中定义的元素的引用,它仍然可以访问上下文的元素(闭包),这实际上是函数定义中的范围。抱歉我的英语不好,但这个例子可能会让你理解:
function test() {
var a = "hello world";
var checkValue = function() { alert(a); };
checkValue();
a = "hi again";
return checkValue;
}
var pointerToCheckValue = test(); //it will print "hello world" and a closure will be created with the context where the checkValue function was defined.
pointerToCheckValue(); //it will execute the function checkValue with the context (closure) used when it was defined, so it still has access to the "a" variable
希望有帮助:-)
关于javascript - 对 JavaScript 中的闭包感到困惑,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/8171959/