For example
enum ABC { A = "a", B = "bb", C = "ccc" };
alert("B" in ABC); // true
alert("bb" in ABC); // false (i wanna true)
Please, keep in mind that we discuss about string enum features.
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1Possible duplicate of Check if value exists in enum in TypeScriptMedet Tleukabiluly– Medet Tleukabiluly2017-11-01 10:08:30 +00:00Commented Nov 1, 2017 at 10:08
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1@MedetTleukabiluly -- Unless I'm mistaken, that's not exactly a duplicate, as TypeScript has different compilation logic for numeric and string enums. The solution proposed there wouldn't work here, see compiled output.John Weisz– John Weisz2017-11-01 10:13:51 +00:00Commented Nov 1, 2017 at 10:13
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3 Answers
Your enum:
enum ABC {
A = "a",
B = "bb",
C = "ccc"
};
Becomes this after compilation (at runtime):
var ABC = {
A: "a",
B: "bb",
C: "ccc"
};
Therefore you need to check if any of the values in ABC is "bb". To do this, you can use Object.values():
Object.values(ABC).some(val => val === "bb"); // true
Object.values(ABC).some(val => val === "foo"); // false
Comments
Your code:
enum ABC {
A = "a",
B = "bb",
C = "ccc"
};
is compiled to the following JavaScript (see demo):
var ABC;
(function (ABC) {
ABC["A"] = "a";
ABC["B"] = "bb";
ABC["C"] = "ccc";
})(ABC || (ABC = {}));
This is why you are getting true for "A" in ABC, and false for "bb" in ABC. Instead, you need to look (i.e. loop) for values yourself; a short one liner could be this:
Object.keys(ABC).some(key => ABC[key] === "bb")
(or you could iterate over values directly using Object.values if supported)
1 Comment
karina
Unfortunately there is no Object.values in typescript :(
In ECMAScript 2016 or higher you can also use includes() for this purpose.
Object.values(ABC).includes('bb' as ABC);
See also: This SO answer
