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I would like to access a List<Records> where Records is a struct, from a JS script. After a bit of googling (especially question 29098558 here) i Json serialized my object and retrieve it in the script.

I should mention it's my first time at JS so syntax may be totally wrong.

In C#

  string serializedResults = JsonConvert.SerializeObject(RecordsList);

(in my context the records are actually in a Dictionnary<string, Records> but i hide the access through dictionnary because i supposed it isn't relevant here)

In Javascript 

<script type="text/javascript">
    function setupBarChart() {
        var x = [];
        var y = [];
        var source = "<%= serializedRecords %>";

        // I would like to put Records fields in y and x tab to use it as data for the axes of an histogram.
        for (var i = 0; i < source.length; i++) {

        }  
    }
</script>

My questions are :

  • what is the type of source ? Is it just a string ? Does it create an equivalent of List in JS ?
  • How do I access my Records fields from JS ?
  • Does source.length gives me the number of records in the list ??
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  • Where are you calling JsonConvert.SerializeObject? You have declared serializedResults but you are trying to use serializedRecords. Looks like some typo. Commented Apr 6, 2017 at 11:23
  • Some typo indeed, it's serializedRecords. I'm calling SerializeObject from the ascx.cs associated to the ascx file where I write my JS. Commented Apr 6, 2017 at 11:27

1 Answer 1

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what is the type of source ? Is it just a string ? Does it create an equivalent of List in JS ?

In the code shown, it is a string, but I think the code shown is very wrong - the quotes are incorrect and should be removed, to:

var source = <%= serializedRecords %>;

(note, I'm not going to opine on encoding in the above, but: be careful and check it is safe)

leaving (in the rendered html):

var source = [{"foo":123,"bar":"def"},{...},{...}];

now the type is a javascript array.

How do I access my Records fields from JS ?

via source, which is an array

Does source.length gives me the number of records in the list ??

yes, if you lose the quotes

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7 Comments

Sorry for the wrong syntax, first time at javascript. I understand why the quotes make source a string. However VisualStudio warn me of a syntax error without the quotes, i must have forgotten something else elsewhere.
@YthioCsi nah, I think Visual Studio is just struggling to parse your intent - does it work? I suspect it will
I wish i could deploy solution but i can't right now... ... ... Anyway, i read the article about JS arrays on W3School website and I wondered if source is an associative array, if so, it tells "all array methods and properties will produce incorrect results", so source.length will return 0 no matter what, doesn't it ? (i can use a foreach instead so it's more a question than a problem)
@YthioCsi it is just a javascript array - length will work just fine; and no, you can't use a foreach - javascript doesn't have a foreach keyword; there are methods like forEach or $.each, of course
Would my view update each time the serializedRecords value changed ? Like a INotifyPropertyChange implementation in WPF ?
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