Javascript Module Pattern accessing updated parameter value

Question

I've tried to search for an answer to my question, but I'm starting to think that, given the lack of results, I'm obviously not expressing the question properly. With that in mind, apologies if the title of this post is misleading, I am still very much learning.

I have a simplified version of my code below

var testData = ['a', 'b']

    var addReceiver = (function () {
        dataReceiver = function (dataInput) {
            t = this
            t.data = dataInput;
            console.log(t.data);
            t.interval = setInterval(function () {
                t.update();
            }, 1000);
            t.stopUpdate = function () { clearInterval(t.interval); };
            t.update = function () {
                //t.data = dataInput;
                console.log(t.data);
            };
        };
    })()

    var testLogger = new dataReceiver(testData);
</script>

The behaviour that I wish to emulate is when I type into the console

testData = ['c','d','e']

for testLogger to log the array ['c','d','e'] every second rather than ['a','b'].

I could change

t.data = dataInput to t.data = testData

to achieve this, but that would obviously be pointless, or else every new instance I created of dataReceiver would have a reference to the same data input.

So, my question is, how would I need to change the code to provide the testLogger vairable (or any instance of dataReceiver) access to a variable outside of its local scope?

Rajaprabhu Aravindasamy · Accepted Answer · 2016-03-01 15:10:11Z

2

Use the object that you have created instead of accessing the global variable,

var testLogger = new dataReceiver(testData);
testLogger.data = [1,2,3,4];

Now you will be able to print the newly injected data. I mean the setInterval will print the updated value.

answered Mar 1, 2016 at 15:10

Rajaprabhu Aravindasamy

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3 Comments

cb1210 Over a year ago

Yes, in theory thats an option. But I may have 3 variables which take testData as an input and a 4th which uses another variable eg

var testLogger1 = new dataReceiver(testData); var testLogger2 = new dataReceiver(testData); var testLogger3 = new dataReceiver(testData); var testLogger4 = new dataReceiver(otherData);

and in this instance it wouldn't be practical to update in the way you've suggested. The data being passed into testData is coming via a websocket and could update at any point, when it does, I'd like testLogger to use these updated values on its next refresh. Does that make sense?

Rajaprabhu Aravindasamy Over a year ago

@cb1210 For that I would suggest you to hold those objects in an array and whenever the value has to be changed, you need to iterate over that array and change the object's property value one by one.

cb1210 Over a year ago

OK, So the answer then is that I can't, but I could possibly add some logic into the websocket onmessage event Listener if I could somehow get a list of objects that are currently using that websocket as their dataInput? Thank you for your help.

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