get json from API: array is interpreted as a string

Question

I have this answer from an API (written by me):

[[new Date(2017,0,28,16,00,00),[0.201766,0.201766,0.201766],[0.309878,0.309878,0.309878],[0.287467,0.287467,0.287467],[null,null,null], ...

I want my view to interpret this answer as javascript, but it doesn't. It assumes it is a string.

$.getJSON('http://localhost:XXXX/...', function (data) {

    // data.jsAlignedData == [[new Date(2017,0,28,16,00,00),[0.201766,0.201766,0.201766], ...

    console.log(data.jsAlignedData);
    // Shows it as a string

    var test = JSON.parse(data.jsAlignedData);
    // Error: Unexpected token e in JSON at position 3 
    // (IMO it's the 'e' from 'new')

    // it doesn't even reach this point:
    console.log(test);          
}

The final goal is to build a Dygraphs plot with a native array for increased speed (see "native array" in the documentation).

JSON objects can contain strings, numbers, booleans, null, arrays and other JSON objects. That's it - no Date, no JS syntax like new. — Joe Clay
– Joe Clay, Commented Jan 30, 2017 at 14:23
@charlietfl Just to clarify (because the discussion under the other answer has just been deleted): the json is valid in the sense that $.getJSON does its work without exception. The tricky part is this one: as it can't interpret the array as a valid json (and this is where you are 100% right), it just presumes it's a string and it continues parsing the rest of the structure. — Xavier Peña
– Xavier Peña, Commented Jan 30, 2017 at 14:34

Aloene · Accepted Answer · 2017-01-30 14:28:02Z

1

You have to serialize to date using JSON standard (see https://en.wikipedia.org/wiki/ISO_8601 for example) to be able to parse it using JSON.parse().

Edit: "JSON standard" for date type is inaccurate because you will have to interpret the date string as a JS date once parsed... (as stated in @charlietfl comment)

edited Jan 30, 2017 at 14:28

answered Jan 30, 2017 at 14:24

Aloene

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5 Comments

charlietfl Over a year ago

right...then convert to date object once received if that's what is required when data gets consumed

Xavier Peña Over a year ago

@charlietfl It looks like I could use this solution for that.

charlietfl Over a year ago

@XavierPeña that is over complicating it ... just change the first array value from string to object when you receive the data arr[0][0] = new Date(arr[0][0]) for example

Xavier Peña Over a year ago

@charlietfl The array is 75K chars long, and is formatted as [[ date1, ... ],[ date2, ... ] ... [ dateN, ... ]]. It contains ~400 dates. I could do a loop, but the idea was to make the backend did all the heavy work.

charlietfl Over a year ago

@XavierPeña iterating 400 items is not a big deal. It is very common to need to do data transformations also. You simply can not store a javascript date object in json

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