es6 变量和作用域的问题

Question

先举个例子说：const testFun = () => {let testParamsconst sonFun = () => {    testParams = 3}console.log(testParams)}像上面这样的写法，我怎么才能console出testParams的值呢？

Answer 1

首先你得先执行了sonFun这个方法，你才能给testParams赋上值

Answer 2

你这赋值根本就没执行嘛

let testParams

const sonFun = () => {

    testParams = 3

}

sonFun()

console.log(testParams)

Answer 3

const testFun = () => {

        let testParams

        const sonFun = () => {

            testParams = 3

        }

        sonFun()

        console.log(testParams)

    }

    testFun()

Answer 4

let testParams

const sonFun = () => {

    testParams = 3

}

sonFun();

console.log(testParams)

这个箭头函数的作用域，在这段代码里面怕是没有提现出来