在JavaScript中,void,eval和Function构造函数之间有什么区别？

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void(document.body.innerText += 'hi')

eval(document.body.innerText +='\nbye')

Function(document.body.innerText += '\n!!!')

void(Function(function foo(){document.body.innerText += '\n>hi2'; return true}).toString())();

eval(Function(function foo(){document.body.innerText += '\nbye2'; return true}).toString())();

Function(Function(function foo(){document.body.innerText += '\n!!!2'; return true}).toString())();

在这些不同的语句中执行代码的处理模型是什么？

void(alert('hi'))
undefined

eval(alert('hi'))
undefined

Function(alert('hi'))
function anonymous() {
  undefined
}

eval(Function(function foo(){return true}).toString())();
TypeError: undefined is not a function

void(Function(function foo(){return true}).toString())();
TypeError: string is not a function

Function(Function(function foo(){return true}).toString())();
undefined

解决方法:

在this article中,解释了eval和Function构造函数：

(…) Global, built-in eval function evaluates code in the scope of a
caller.

The code executed from within function created by Function constructor
doesn’t really execute in global scope. However, it doesn’t execute in
local scope either, which is what probably leads to confusion.
Function constructor creates a function whose scope chain consists of
nothing but a global scope (preceded with function’s own Activation
Object, of course). Any code contained in a function created via
Function constructor evaluates in a scope of that function, not in a
global scope. However, it’s almost as if code executes globally, since
global object is the very next object in the scope chain.

根据this page,void只返回undefined：

In many languages, void is a type that has no values. In JavaScript,
void is an operator that takes an operand and returns undefined. This
is not useful, and it is very confusing. Avoid void.

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