tools.parseUnitString and tools.parseAngle

src/tools.js

@@ -6,7 +6,8 @@ define([], function() {
       noop = function() {},
       push = [].push,
       slice = [].slice,
-      toString = {}.toString;
+      toString = {}.toString,
+      PI = Math.PI;
 
   /**
    *
@@ -339,6 +340,52 @@ define([], function() {
       array.length -= numRemoved;
 
       return array;
+    },
+
+    /**
+     * Parse a given unit string into the amount and unit
+     *
+     * @param {any} any Anything that can be converted to a string. E.g. '7deg', ['50%']
+     * @returns {String} unit
+     */
+    extractUnit: function (any) {
+      if (typeof any === 'undefined' || typeof any === 'number') {
+        return '';
+      }
+
+      // make sure it's a string and remove trailing whitespace
+      var unit = String(any).replace(/\s+$/, '');
+      // returns extracted unit or empty string
+      return unit.match(/[a-z%]*$/i)[0];
+    },
+
+    /**
+     * Parses the angle string to radians
+     * https://developer.mozilla.org/en-US/docs/CSS/angle
+     *
+     * @param {Number|String} angle The angle/unit string
+     * @returns {Number} The angle in radians
+     */
+    parseAngle: function(angle) {
+      var radians,
+          unit = tools.extractUnit(angle),
+          amount = parseFloat(angle);
+
+      switch (unit) {
+        case '': // default
+        case 'rad':
+          radians = amount; break;
+        case 'deg':
+          radians = amount * PI / 180; break;
+        case 'grad':
+          radians = amount * PI / 200; break;
+        case 'turn':
+          radians = amount * 2 * PI; break;
+        default:
+          radians = 0;
+      }
+
+      return radians;
     }
   };
 

test/tools-spec.js

@@ -284,4 +284,98 @@ define([
     });
   });
 
+  /*--------------------------------------------------------------------------*/
+
+  describe('tools.extractUnit', function() {
+    var extractUnit = tools.extractUnit;
+
+    it('return the unit from a unit string', function() {
+      var returned = extractUnit('9deg');
+      var expected = 'deg';
+
+      expect(returned).toEqual(expected);
+    });
+
+    it('should work with negative numbers', function() {
+      var returned = extractUnit('-741232grad');
+      var expected = 'grad';
+
+      expect(returned).toEqual(expected);
+    });
+
+    it('should work with trailing whitespace', function() {
+      var returned = extractUnit('-741232grad    ');
+      var expected = 'grad';
+
+      expect(returned).toEqual(expected);
+    });
+
+    it('should work with leading whitespace', function() {
+      var returned = extractUnit('-741232 grad    ');
+      var expected = 'grad';
+
+      expect(returned).toEqual(expected);
+    });
+
+    it('should return an empty string in case of a number', function () {
+      var returned = extractUnit(7531);
+      var expected = '';
+
+      expect(returned).toEqual(expected);
+    });
+
+    it('should return the string when given an array', function () {
+      var returned = extractUnit(['50s']);
+      var expected = 's';
+
+      expect(returned).toEqual(expected);
+    });
+
+    it('should work with percentages', function () {
+      var returned = extractUnit('50%');
+      var expected = '%';
+
+      expect(returned).toEqual(expected);
+    });
+  });
+
+  describe('tools.parseAngle', function() {
+    var parseAngle = tools.parseAngle;
+
+    it('calculates radians for degrees', function() {
+      var calculated = parseAngle('45deg');
+      var expected = 0.7853981633974483;
+
+      expect(calculated).toBeCloseTo(expected, 10);
+    });
+
+    it('calculates radians for turns', function() {
+      var calculated = parseAngle('1turn');
+      var expected = 6.283185307179586;
+
+      expect(calculated).toBeCloseTo(expected, 10);
+    });
+
+    it('calculates radians for gradians', function () {
+      var calculated = parseAngle('-32grad');
+      var expected = -0.5026548245743669;
+
+      expect(calculated).toBeCloseTo(expected, 10);
+    });
+
+    it('calculates radians for radians (string)', function () {
+      var calculated = parseAngle('-0.5026548245743669rad');
+      var expected = -0.5026548245743669;
+
+      expect(calculated).toBeCloseTo(expected, 10);
+    });
+
+    it('calculates radians for radians', function () {
+      var calculated = parseAngle('-0.5026548245743669');
+      var expected = -0.5026548245743669;
+
+      expect(calculated).toBeCloseTo(expected, 10);
+    });
+  });
+
 });