如何捕获调用异步函数时存在的值

Question

let x = "value before setTimeout";

function cb() {
    console.log(currentValue); 
}

setTimeout(cb, 3000);

x = "updated value";

如何借助回调函数打印“setTimoeout 之前的值”。如何捕获旧值并使用它？

Answer 1

将其存储为临时系数：

let a = 20

function log(a) {
  console.log('a is: ' + a)
}

setTimeout(log, 1000, a)

a = 43