javascript - 函数和闭包可以替代 Javascript 中的类吗？

Question

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Answer 1

闭包是 Javascript 代码中的一种结构，在嵌套函数中，外部函数范围保留在内部函数中。

例如:

function outer(x,y){
    var t = 1;
    return function(z){
        //x, y, t from the outer function are made available to inner function
        return x + y + z + t; 
    }
}

var outer1 = outer(1,1);  //creating a closure, or an instance of a function in sense
alert(outer1(1)); //Alerts 4

var outer2 = outer(2,2);
alert(outer2(2)); //Alerts 7

The simple explanation of a Closure is that ECMAScript allows inner functions; function definitions and function expressions that are inside the function bodes of other functions. And that those inner functions are allowed access to all of the local variables, parameters and declared inner functions within their outer function(s). A closure is formed when one of those inner functions is made accessible outside of the function in which it was contained, so that it may be executed after the outer function has returned. At which point it still has access to the local variables, parameters and inner function declarations of its outer function. Those local variables, parameter and function declarations (initially) have the values that they had when the outer function returned and may be interacted with by the inner function.

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