How come self gets updated inside object?

Question

I have a object that I create two instances of:

    var generalGraph = new graph(generalFunnel)
    generalGraph.draw("#conversion");

    var invoicingGraph = new graph(invoicingFunnel)
    invoicingGraph.draw("#invoicing")

Here is the object (note that this is highly simplified to make it easier to understand) the comments are the console-outputs.

graph = function(funnel){
    this.funnel = funnel.conversions
    mySelf = this

    this.draw = function(selector){
        console.log(mySelf.funnel)
        //generalGraph ["Användare", "Påbörjat Onboarding", "Skapat oganisation", "Skapat användare", "Kom tillbaka", "Köpt"]
        //invoicingGraph ["Användare", "Påbörjat Onboarding", "Skapat oganisation", "Kom tillbaka", "Köpt"]
        nv.addGraph(function() {

            console.log(mySelf.funnel)
            //generalGraph ["Användare", "Påbörjat Onboarding", "Skapat oganisation", "Kom tillbaka", "Köpt"]
            //invoicingGraph ["Användare", "Påbörjat Onboarding", "Skapat oganisation", "Kom tillbaka", "Köpt"]
        });
    }

}

For some reason, when I do generalGraph.draw, it uses the funnel from invoicingFunnel. Why? And how can I stop it from happening?

I don't know, the reason i do mySelf = this is that, this is sometimes changed, for example inside nv.addGraph. — Himmators, Dec 16 '14 at 16:27

score 4 · Accepted Answer · edited May 23 '17 at 11:57

mySelf is a global variable, you're missing a var before it. For this reason both of your graph instances use the same mySelf value.

Change:

mySelf = this

To

var mySelf = this

See this question on the differences between using and ommitting var.
You can prevent these errors in the future by using strict mode which will spot these errors for you.
Omitting semicolons in JavaScript is possible but is considered very risky because of the complicated rules it involves. It is generally frowned upon to do it today.
Similarly - constructor names in JS typically start with a capital letter. Your constructor should probably be defined with the var keyword as well.

How come self gets updated inside object?

1 Answers1