如何深入检查“null"或“未定义"用JS? [英] How to deep check for "null" or "undefined" with JS?
问题描述
在 Node.JS 项目中，假设我有来自 API 或任何其他具有类似结构的对象的响应
In a Node.JS project, let's say I have a response from an API or any other object with a structure like
{
data: {
info: {
user: {
name: "Hercules",
password: "Iamthegreatest!"
email: "hercules@olymp.gr"
}
}
}
}
访问对象的成员非常容易.但是，在访问任何值之前检查是否存在会得到 PITA.
Accessing the members of the object is pretty easy. However, checking the existence before accessing any value gets PITA.
我可以假设数据始终存在.信息、用户、姓名、密码和电子邮件可能存在，也可能不存在.可以存在没有用户的有效信息对象，也可以存在没有电子邮件地址的有效用户.
I can assume that data is always present. Info, user, name, password and email may be present or may not. There can be a valid info object without an user and there can be a valid user without an email address.
这会导致类似的代码
if (data && data.info && data.info.user && data.info.user.email) {
var email = data.info.user.email;
}
只检查
if (data.info.user.email)
// do something
}
如果任何对象不存在，则抛出错误.
Throws an error if any of the objects do not exist.
是否有更短的方法来深入检查此类结构的存在?
Is there a shorter way to deep check the existence of structures like this?
推荐答案
从项目目录中的控制台，npm install dotty
From the console in your project directory, npm install dotty
然后在代码的顶部，使用以下命令导入 dotty:var dotty = require('dotty')
Then at the top of your code, import dotty with: var dotty = require('dotty')
那么如果obj是上面贴出的对象，就可以调用
then if obj is the object posted above, you can call
dotty.exists(obj, "data.info.user.email")
它会产生 true 或 false 而不是抛出错误.
and it will yield true or false instead of throwing an error.
参见 https://www.npmjs.org/package/dotty
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