How can convert datetime form Net to JavaScript

Question

Please don't make duplicate vs ASP.NET Parse DateTime result from ajax call to javascript date and Parsing DateTime format passed from Ajax to "dd/MM/yyyy", I have been read carefully. But my question is differences.

I have data from asp.net load by ajax below.

 Datetime in c#: "2019-05-04" 
 The result in ajax is: "/Date(1556895600000+0900)/"

You can see the result automatic add time UTC offset to DateTime, I don't know why.

How can I convert to DateTime in javascript vs data above?

var d = new Date(("/Date(1556895600000+0900)/").match(/\d+/)[0] * 1)
console.log(d)

You can see: Result "2019-05-03T15:00:00.000Z", But I expect result "2019-05-04". How can I do this?

• Heretic Monkey: That's an invalid date value. Do you have access to the C# code?
• Heretic Monkey: Otherwise, you're going to need to add 9 hours to d to get the correct value.
• Hong Van Vit: @ Heretic Monkey: public DateTime TheDate { get; set; }, My sytem publish for Korea, and Vietnam, China, Japan. But in Korea add 9, Vietnam add 7...=> This is not good solution.
• Heretic Monkey: You can set up C# to output whatever date format you want, including ISO 8601 in UTC, which you can pass directly to new Date() without a lot of this parsing work.

Answer 1

Look I'm no dates expert but the following looks convincing to me

const parse = str => {
 let [_, timestamp, offsetHours, offsetMinutes] = str.match(/(\d+)([+-]\d\d)(\d\d)/).map(Number);
 
 let date = new Date(timestamp);
 date.setHours(date.getHours() + offsetHours);
 date.setMinutes(date.getMinutes() + offsetMinutes);
 return date;
}
console.log(
 parse("/Date(1556895600000+0900)/")
 .toJSON()
)
console.log(
 parse("/Date(1556895600000-0700)/")
 .toJSON()
)

Here's a ES3 version in case it doesn't work in older browsers (as the OP said in the comments)

function parse(str) {
 var matches = str.match(/(\d+)([+-]\d\d)(\d\d)/).map(Number);
 var timestamp = matches[1];
 var offsetHours = matches[2];
 var offsetMinutes = matches[3];
 
 var date = new Date(timestamp);
 date.setHours(date.getHours() + offsetHours);
 date.setMinutes(date.getMinutes() + offsetMinutes);
 return date;
}
console.log(
 parse("/Date(1556895600000+0900)/")
 .toJSON()
)
console.log(
 parse("/Date(1556895600000-0700)/")
 .toJSON()
)

• Hong Van Vit: Thank Devansh J. But it only work on Chrome. How can you fix it on IE?
• Hong Van Vit: Sorry again. How can work with timeofset <0 for example: /Date(1556895600000-0700)?