在JavaScript中访问对象的转义属性

Question

I have an object with a property like this:

var RouteMetaSet = {

    '\/user-management\/users': {
        path: '/user-management/users',
        name: 'User Management',
        iconClassList: ['fa', 'fa-user'],
    }
};

I can easily get the value of the property like this:

console.log(RouteMetaSet['\/user-management\/users'])

However, if I assign the key to a variable and then push it inside the brackets, it's impossible.

var originialString = /user-management/users;
var escapedString = originialString.replace(/[-/<>*()?]/g, "\\$&"); // it should be "\/user-management\/users"
console.log(RouteMetaSet[escapedString]); // undefined

Am I wrong somewhere on this point?

Answer 1

First. This:

var originialString = /user-management/users;

… is just syntax errors.

String literals in JS must be quoted.

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Next:

Escape characters have meaning in JavaScript source code .

When the string literal is parsed by the JavaScript engine it is turned into the string. During this process, the escape characters are consumed.

They aren't part of the data at all. If you insert slashes with regular expressions, then you are just inserting slashes (not escape sequences) into the string.

 var RouteMetaSet = { '\\/user-management\\/users': { path: '/user-management/users', name: 'User Management', iconClassList: ['fa', 'fa-user'], } }; var originialString = "/user-management/users"; console.log(RouteMetaSet[originialString]); 

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Aside: the / character does not need to be escaped in a JS string literal unless it forms part of the sequence </script> inside an inline script.

Generated code often escapes all / characters as a simple and effective way to avoid that problem.

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If the property name included characters that did need to be escaped (such as a \\ ) then, by the time the string had been parsed, it would be too late to sensibly do anything about it.

var originalString = "Example\t";

Is that supposed to be a tab or is it supposed to be a \\ followed by a t ?

If you can't trust the code to be right in the first place, you have a problem.