函数声明的问题

Question

变量声明中

    var fn = function fn2() {}
    
    console.log(fn) // function
    console.log(fn2) // Uncaught ReferenceError: fn2 is not defined

这里的fn2为什么是not defined？ 是因为在fn2自己的作用域中么？

Answer 1

javascript the definitive guide 8.1

An identifier that names the function. The name is a required part of function declaration statements: it is used as the name of a variable, and the newly defined function object is assigned to the variable. For function definition expressions, the name is optional: if present, the name refers to the function object only within the body of the function itself.

就是说，「赋值函数定义式」中的 identifier（函数名）是可选的，即使提供，也只能在函数体内引用；

Answer 2

fn2只能在fn2中才能引用的到

Answer 3

function fun2(){}
var fn = fn2
console.log(fn)
console.log(fn2)