src/event.js
// the callback is invoked, it will be removed.
the callback is invoked, it will be removed.
the callback is invoked it will be removed .
once(name, callback, context) {
        if (!eventsApi(this.event, 'once', name, [callback, context]) || !callback) return this;
        const self = this;
        var once = _once(function() {
            self.event.off(name, once);
            callback.apply(this, arguments);
        });
        once._callback = callback;
        return this.event.on(name, once, context);
    }
once ( name , callback , context ) { if ( ! eventsApi ( this . event , 'once' , name , [ callback , context ] ) || ! callback ) return this ; const self = this ; var once = _once ( function ( ) { self . event . off ( name , once ) ; callback . apply ( this , arguments ) ; } ) ; once . _callback = callback ; return this . event . on ( name , once , context ) ; }
the callback is invoked, it will be removed.
the callback is invoked it will be removed .