Typescript not recognizing Date as Date?

Question

I don't know what's going on here... but apparently TS is not recognizing Date as Date, instead it thinks it is a string.

Here's the code I use to save the Date:

var validUntil = new Date();

validUntil.setSeconds(validUntil.getSeconds() + tokenResponse.expires_in);
tokenResponse.valid_until = validUntil;

And this is my TokenResponse class:

export class TokenResponse {
    access_token: string;
    token_type: string;
    expires_in: number;
    valid_until: Date;
    error: string;
    error_description: string;
}

And here is where the exception is thrown:

userToken && userToken.valid_until.getTime()  >= new Date().getTime()

Here's the exception:

Any ideas on what's wrong?

Thanks!

EDIT

By the way, I don't think it's related to Date variable works, but functions on it do not since I'm creating a new Date

Post a complete minimal example reproducing the problem. We have no idea what userToken is, among other things. — JB Nizet
– JB Nizet, Commented Nov 11, 2016 at 16:50
If it comes from your API, I guess it's JSON, and JSON doesn't have Dates. Only string, number, boolean. And a JSON object will never be an instance of any class. Again, a complete example would help. — JB Nizet
– JB Nizet, Commented Nov 11, 2016 at 16:54
@JBNizet I thought the information there would be enough. Is there anything specific that would help? I receive the response from the server (1st piece of code), my class is TokenResponse and when I try to use it it's not loading as Date (apparently) — eestein
– eestein, Commented Nov 11, 2016 at 16:55
@JBNizet you are correct about JS, though I'm creating a new instance of Date. I'm not relying on the response. — eestein
– eestein, Commented Nov 11, 2016 at 16:57

David Sherret · Accepted Answer · 2016-11-11 16:58:05Z

2

In code that isn't posted here, the value of userToken.validUntil is being set as a string. You will see that if you check typeof userToken.validUntil before the part of the code where calling getTime() errors.

Make sure when setting userToken.validUntil that you always assign a Date object to it. If you're deserializing JSON to userToken, then make sure the deserializer converts date strings to date objects or for a quick fix do (though not recommended):

userToken.validUntil = new Date(userToken.validUntil as any);

Note the following:

var o = { d: new Date() };
localStorage.setItem("test", JSON.stringify(o));
o = JSON.parse(localStorage.getItem("test"));
typeof o.d === "string"; // true

edited Nov 11, 2016 at 16:58

answered Nov 11, 2016 at 16:55

David Sherret

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3 Comments

eestein Over a year ago

Thanks David, the only time I set validUntil is there :/ The only thing I can think of is maybe the local storage is changing the type?

eestein Over a year ago

I just checked your update. Isn't that the same as what I was doing?

var validUntil = new Date();  validUntil.setSeconds(validUntil.getSeconds() + tokenResponse.expires_in); tokenResponse.valid_until = validUntil;

eestein Over a year ago

Ok... so the problem is related to the storage... is there a way to force it to save Date?

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