C ++ 11 значения и путаница в семантике перемещения (оператор return)

В качестве класса (ES6):

class ResponsiveImageMap {
    constructor(map, img, width) {
        this.img = img;
        this.originalWidth = width;
        this.areas = [];

        for (const area of map.getElementsByTagName('area')) {
            this.areas.push({
                element: area,
                originalCoords: area.coords.split(',')
            });
        }

        window.addEventListener('resize', e => this.resize(e));
        this.resize();
    }

    resize() {
        const ratio = this.img.offsetWidth / this.originalWidth;

        for (const area of this.areas) {
            const newCoords = [];
            for (const originalCoord of area.originalCoords) {
                newCoords.push(Math.round(originalCoord * ratio));
            }
            area.element.coords = newCoords.join(',');
        }

        return true;
    };
}

Использование:

var map = document.getElementById('myMapId');
var image = document.getElementById('myImageId');
new ResponsiveImageMap(map, image, 800);