Object method with ES6 / Bluebird promises

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Why this ends up being undefined in this case?

Because you’re passing a function, not a method-bound-to-an-instance. This problem is not even promise-specific, see How to access the correct `this` context inside a callback? for the generic solution:

….then(this.method2.bind(this))… // ES5 .bind() Function method

….then((r) => this.method2(r))… // ES6 arrow function

However, Bluebird does offer an other way to call the function as a method:

this.service.serviceMethod(args)
    .bind(this)
    .then(this.method2)
    .catch(onRejected);

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