Javascript Self Invoked Functions

Question

Hi guys can you explain me the differences between this two kind of implementations?

 var vettoreC: Array<number> = []; vettoreC = vettoreA; this.moda = (function mode(vettoreC) { return vettoreC.sort((a, b) => vettoreC.filter(v => v === a).length - vettoreC.filter(v => v === b).length ).pop(); })();

and

var vettoreC: Array<number> = []; vettoreC = vettoreA; this.moda = this.calcolaModa (vettoreC);

where calcolaModa is

calcolaModa(vettore: Array<number>) { return vettore.sort((a, b) => vettore.filter(v => v === a).length - vettore.filter(v => v === b).length ).pop(); }

In the first case I have this error:

ERROR TypeError: Cannot read property 'sort' of undefined at mode (statistiche.component.ts:145) at statisticheComponent.webpackJsonp.128.statisticheComponent.calcolaStatistiche (statistiche.component.ts:148) at SafeSubscriber._next (statistiche.component.ts:72) at SafeSubscriber.__tryOrUnsub (Subscriber.js:238) at SafeSubscriber.next (Subscriber.js:185) at Subscriber._next (Subscriber.js:125) at Subscriber.next (Subscriber.js:89) at MapSubscriber._next (map.js:83) at MapSubscriber.Subscriber.next (Subscriber.js:89) at CatchSubscriber.Subscriber._next (Subscriber.js:125)

The second works correctly.

What could i do to make valid the first implementation?

Douwe de Haan · Accepted Answer · 2017-05-31 09:04:11Z

With the first example, you'll need to pass the arguments in the last parentheses:

this.moda = (function mode(vettoreC) { return vettoreC.sort((a, b) => vettoreC.filter(v => v === a).length - vettoreC.filter(v => v === b).length ).pop(); })(vettoreC);

Notice the last line where the vettoreC is mentioned again.

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