growstuff/app/assets/javascripts/graphs/width_scale.js

// =require d3

/**
 * Width scale is used to map the value for the length of each bar
 * to the display size of the svg
 */
(function() {
  'use strict';

  var growstuff = (window.growstuff = window.growstuff || {});

  /**
   * Object for WidthScale
   * @param {Object} data Graph configuration
   */
  function WidthScale(data) {
    this._data = data;
  }

  WidthScale.prototype.render = function() {
    var data = this._data;
    var scaleType = data.width.scale;
    var axisSize = data.width.size;

    return d3.scale[scaleType]()
        .domain([0, this.getMaxValue()])
        .range([0, axisSize]);
  };

  WidthScale.prototype.getMaxValue = function() {
    return d3.max(this._data.bars.map(function(bar) {
      return bar.value;
    }));
  };

  growstuff.WidthScale = WidthScale;
}());