Javascript：如何使用eval返回或解析对象文字？ [英] Javascript: How to return or parse an object literal with eval?

问题描述

我有一个小库，它可以接收字符串并从中构造对象。例如，’-key val’创建 { key： val} 。但是，我也在尝试扩展输入字符串的语法以采用简单的对象文字，例如'-key {key：'val'}' yield { key：{ key： val}} 但是结果仅为 { key： val} 。

I have a little library that takes strings and constructs objects out of them. For example '-key val' creates {"key": "val"}. However I'm trying to extend the syntax of the input string to take simple object literals too, such as '-key "{key: 'val'}"' which should yield {"key" : {"key" : "val"}} however the result is only {"key" : "val"}.

为什么eval只返回 val而不返回整个对象？还有比我的解决方案更安全的选择吗？

Why does eval only return "val" and not the entire object? And is there a safer alternative then my solution?

// my code before the fix
var arg = '{key: "val"}'
var result = eval(arg)
// result is "val"

下面是我的解决方法，这非常不安全！

Below is my fix, which is very unsafe!

const fmt = require('util').format
var arg = '{key: "val"}'
var result = eval(fmt('()=>(%s)', arg))()
// result is { key : "val" }

推荐答案

{key： val} 是一个块，而 key：是一个标签。

{key: "val"} is a block, and key: is a label.

如果要将其解析为对象初始值设定项，请在需要表达式的地方使用它，例如

If you want to parse it as an object initializer, use it in a place which expects an expression, e.g.

({key: "val"})
0,{key: "val"}
[{key: "val"}][0]

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