在JS中调用其他函数时返回前一个参数

Question

如何在JS中实现以下逻辑

的例子:

Let y = alertMyPreviousParam(“1”);
Let z= y(‘2’) 
// show output as  1
Let a = z(‘3’)
// show output as 2
Let b = a(‘ra’) 
// show output as 3
Let c = b(‘z’) 
// show output as ‘ra’,

Answer 1

尽管各种Syntax error

1)由‘和’包围的字符串不是有效的javascript字符串，与“和”类似。使用"或'。

2)变量应该用let而不是Let来声明。

解决方案

---

您可以在这里利用closure和Higher order function(HOF)

function alertMyPreviousParam(arg) {
let last = arg;
return function (curr) {
console.log(last);
last = curr;
return alertMyPreviousParam(curr);
};
}
let y = alertMyPreviousParam("1");
let z = y("2");
// show output as  1
let a = z("3");
// show output as 2
let b = a("ra");
// show output as 3
let c = b("z");
// show output as ‘ra’,

Answer 2

您将需要查看闭包。下面是一个例子:

let var = null
let next = null
const myFunc = (newnext) => {
var = next
next = newnext
return var
}

抱歉格式不对，我在用手机

Answer 3

函数alertMyPreviousParam，返回一个新函数，并输出之前的输入。这可以通过以下方式实现:

let alertMyPreviousParam = (x) => (y) => {
console.log(x);
return alertMyPreviousParam(y);
}