Create OL3 Style object(s) from object literals.

style.js

      var styleMap = {
        fill: function(obj) {
          if (typeof obj == 'string' || Array.isArray(obj)) {
            obj = { color: obj };
          }
          return new ol.style.Fill(obj);
        },
        stroke: function(obj) {
          if (typeof obj == 'string' || Array.isArray(obj)) {
            obj = { color: obj };
          } else if (typeof obj == 'number') {
            obj = { width: obj };
          }
          return new ol.style.Stroke(obj);
        },
        text: function(obj) {
          if (typeof obj == 'string') {
            obj = { text: obj };
          }
          if (obj.fill) {
            obj.fill = styleMap.fill(obj.fill);
          }
          if (obj.stroke) {
            obj.stroke = styleMap.stroke(obj.stroke);
          }
          return new ol.style.Text(obj);
        },
        circle: function(obj) {
          if (obj.fill) {
            obj.fill = styleMap.fill(obj.fill);
          }
          if (obj.stroke) {
            obj.stroke = styleMap.stroke(obj.stroke);
          }
          return new ol.style.Circle(obj);
        },
        icon: function(obj) {
          return new ol.style.Icon(obj);
        },
        image: function(obj) {
          if (typeof obj.radius !== 'undefined') {
            return styleMap.circle(obj);
          }
          return styleMap.icon(obj);
        }
      };

      function makeStyle(styleSpec) {
        if (Array.isArray(styleSpec)) {
          return styleSpec.map(function(oneSpec) {
            return makeStyle(oneSpec);
          });
        }
        
        var obj = {};
        Object.keys(styleSpec).forEach(function(key) {
          var val = styleSpec[key];
          if (styleMap[key]) {
            obj[key] = new styleMap[key](val);
          } else {
            obj[key] = val;
          }
        });
        return new ol.style.Style(obj);
      }
      
      var compoundStyle = makeStyle([{
        stroke: {
          color: [0, 0, 127, 0.15],
          width: 8
        },
        zIndex: 1
      }, {
        fill: [203, 194, 185, 1],
        stroke: [101, 95, 90, 1],
        zIndex: 2
      }]);