Method _layers

src/core/core.scale.js:1637–1671

* @return {object[]} * @private

()

	 * @private
	 */
  _layers() {
    const opts = this.options;
    const tz = opts.ticks && opts.ticks.z || 0;
    const gz = valueOrDefault(opts.grid && opts.grid.z, -1);
    const bz = valueOrDefault(opts.border && opts.border.z, 0);

    if (!this._isVisible() || this.draw !== Scale.prototype.draw) {
      // backward compatibility: draw has been overridden by custom scale
      return [{
        z: tz,
        draw: (chartArea) => {
          this.draw(chartArea);
        }
      }];
    }

    return [{
      z: gz,
      draw: (chartArea) => {
        this.drawBackground();
        this.drawGrid(chartArea);
        this.drawTitle();
      }
    }, {
      z: bz,
      draw: () => {
        this.drawBorder();
      }
    }, {
      z: tz,
      draw: (chartArea) => {
        this.drawLabels(chartArea);
      }
    }];
  }

  /**
	 * Returns visible dataset metas that are attached to this scale