Question

84

Call Method from Constructor: Error: Uncaught TypeError: undefined is not a function

rated 0 times [ 90] [ 6] / answers: 1 / hits: 17474 / 10 Years ago, wed, may 21, 2014, 12:00:00

Task: I need to build a class in Typescript that calls some of it's own methods in it's own Constructor.

Problem: The Actual Code that the following Sample Code represents will Compile Successfully, but upon testing in the Javascript Console, it does not.

Sample:

export class volumeEQ

{

    constructor(ctx:any) 

    {

        this.ctx = ctx;         // Audio context saved into member variable of class

        this.setupAudioNodes(); // Sets up nodes made out of audio

    }



    setupAudioNodes()

    {

        this.sourceNode.connect(this.ctx.destination); // Connect to destination

    }

}

Technical: The Typescript Compiler does not have a problem with this.setupAudioNodes() but once called as Javascript within the Browser's Javascript Console I receive an error Uncaught TypeError: undefined is not a function. Effectively, this is an issue with Javascript's this. syntax and how it's easy to get confused with it. But because I'm developing in Typescript, I want a more Typescript style solution.

Question: How can I call a Class's Methods from it's Constructor in Typescript?

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alorac

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answered 10 Years ago alexandreah · Accepted Answer

Here's how to call a method from the constructor:

class Thing {

    constructor(name: string) {

        this.greet(name);

    }



    greet(whatToGreet: string) {

        console.log('Hello, ' + whatToGreet + '!')

    }

}



var x = new Thing('world'); // Prints Hello, world!