Added unit drop (gtt)

HISTORY.md

@@ -8,14 +8,19 @@ https://github.com/josdejong/mathjs
 - Implemented function `unaryplus` and unary plus operator.
 - Added constant `phi`, the golden ratio (`phi = 1.618...`).
 - Added constant `version`, returning the version number of math.js as string.
+- Added unit `drop` (`gtt`).
 - Fixed not being able to load math.js using AMD/require.js.
 - Removed matrix support from conditional function `ifElse`.
 - Removed automatic assignment of expression results to variable `ans`. 
-  This functionality can be restored by preprocessing every evaluation, 
+  This functionality can be restored by pre- or postprocessing every evaluation, 
   something like:
   ```js
   function evalWithAns (expr, scope) {
-    return math.eval('ans=(' + expr + ')', scope);
+    var ans = math.eval(expr, scope);
+    if (scope) {
+      scope.ans = ans;
+    }
+    return ans;
   }
   ```
 

docs/datatypes/units.md

@@ -90,7 +90,7 @@ Base                | Unit
 Length              | meter (m), inch (in), foot (ft), yard (yd), mile (mi), link (li), rod (rd), chain (ch), angstrom, mil
 Surface             | m2, sqin, sqft, sqyd, sqmi, sqrd, sqch, sqmil
 Volume              | m3, litre (l, L), cc, cuin, cuft, cuyd, teaspoon, tablespoon
-Liquid              | volume	minim (min), fluiddram (fldr), fluidounce (fldz), gill (gi), cup (cp), pint (pt), quart (qt), gallon (gal), beerbarrel (bbl), oilbarrel (obl), hogshead
+Liquid              | volume	minim (min), fluiddram (fldr), fluidounce (fldz), gill (gi), cup (cp), pint (pt), quart (qt), gallon (gal), beerbarrel (bbl), oilbarrel (obl), hogshead, drop (gtt)
 Angles              | rad, deg, grad, cycle
 Time                | second (s), seconds, minute, minutes, hour (h), hours, day, days
 Mass                | gram(g), tonne, ton, grain (gr), dram(dr), ounce (oz), poundmass (lbm), hundredweight (cwt), stick

lib/type/Unit.js

@@ -672,6 +672,8 @@ var UNITS = {
   teaspoon: {name: 'teaspoon', base: BASE_UNITS.VOLUME, prefixes: PREFIXES.NONE, value: 0.000005, offset: 0}, // 5 mL
   tablespoon: {name: 'tablespoon', base: BASE_UNITS.VOLUME, prefixes: PREFIXES.NONE, value: 0.000015, offset: 0}, // 15 mL
   //{name: 'cup', base: BASE_UNITS.VOLUME, prefixes: PREFIXES.NONE, value: 0.000240, offset: 0}, // 240 mL  // not possible, we have already another cup
+  drop: {name: 'drop', base: BASE_UNITS.VOLUME, prefixes: PREFIXES.NONE, value: 5e-8, offset: 0},  // 0.05 mL = 5e-8 m3
+  gtt: {name: 'gtt', base: BASE_UNITS.VOLUME, prefixes: PREFIXES.NONE, value: 5e-8, offset: 0},  // 0.05 mL = 5e-8 m3
 
   // Liquid volume
   minim: {name: 'minim', base: BASE_UNITS.VOLUME, prefixes: PREFIXES.NONE, value: 0.00000006161152, offset: 0}, // 0.06161152 mL
@@ -805,6 +807,7 @@ var PLURALS = {
   beerbarrels: 'beerbarrel',
   oilbarrels: 'oilbarrel',
   hogsheads: 'hogshead',
+  gtts: 'gtt',
 
   grams: 'gram',
   tons: 'ton',

test/error/IndexError.test.js

@@ -58,4 +58,9 @@ describe('IndexError', function () {
     assert.equal(err.toString(), 'IndexError: Index out of range (6 > 3)');
   });
 
+  it('should throw an error when constructed without new operator', function() {
+    assert.throws(function () {
+      IndexError(5);
+    });
+  });
 });