Method once

examples/using-pm2-and-transpilers/node.d.ts:293–293

(event: string, listener: Function)

        addListener(event: string, listener: Function): this;
        on(event: string, listener: Function): this;
        once(event: string, listener: Function): this;
        removeListener(event: string, listener: Function): this;
        removeAllListeners(event?: string): this;
    }