Print falsy values as empty strings.

Author: blueimp

README.md

@@ -256,6 +256,14 @@ Use dot notation to print nested properties:
 <strong>{%=o.author.name%}</strong>
 ```
 
+Note that the JavaScript Templates engine prints **falsy** values as empty strings.  
+That is, **undefined**, **null**, **false**, **0** and **NaN** will all be converted to **''**.  
+To be able to print e.g. the number 0, convert it to a String before using it as an output variable:
+
+```html
+<h3>{%=0+''%}</h3>
+```
+
 ### Evaluation
 Use **print(str)** to add escaped content to the output:
 

package.json

@@ -15,5 +15,5 @@
         "test": "node ./test/test.js"
     },
     "main": "tmpl",
-    "version": "1.0.1"
+    "version": "1.0.2"
 }

test/test.js

@@ -1,5 +1,5 @@
 /*
- * JavaScript Templates Test 1.0.1
+ * JavaScript Templates Test 1.0.2
  * https://github.com/blueimp/JavaScript-Templates
  *
  * Copyright 2011, Sebastian Tschan
@@ -23,6 +23,9 @@
         },
         data = {
             value: 'value',
+            nullValue: null,
+            falseValue: false,
+            zeroValue: 0,
             special:  '<>&"\x00',
             list: [1, 2, 3, 4, 5],
             func: function () {
@@ -134,6 +137,32 @@
         );
     });
 
+    $.test('Print empty string for escaped falsy values', function () {
+        $.strictEqual(
+            $.tmpl(
+                '{%=o.undefinedValue%}{% print(o.undefinedValue); %}' +
+                    '{%=o.nullValue%}{% print(o.nullValue); %}' +
+                    '{%=o.falseValue%}{% print(o.falseValue); %}' +
+                    '{%=o.zeroValue%}{% print(o.zeroValue); %}',
+                data
+            ),
+            ''
+        );
+    });
+
+    $.test('Print empty string for unescaped falsy values', function () {
+        $.strictEqual(
+            $.tmpl(
+                '{%#o.undefinedValue%}{% print(o.undefinedValue, true); %}' +
+                    '{%#o.nullValue%}{% print(o.nullValue, true); %}' +
+                    '{%#o.falseValue%}{% print(o.falseValue, true); %}' +
+                    '{%#o.zeroValue%}{% print(o.zeroValue, true); %}',
+                data
+            ),
+            ''
+        );
+    });
+
     $.module('Evaluation', lifecycle);
 
     $.test('Escape HTML special characters with print(data)', function () {
@@ -166,7 +195,10 @@
 
     $.test('Else condition', function () {
         $.strictEqual(
-            $.tmpl('{% if (o.empty) { %}false{% } else { %}true{% } %}', data),
+            $.tmpl(
+                '{% if (o.undefinedValue) { %}false{% } else { %}true{% } %}',
+                data
+            ),
             'true'
         );
     });

tmpl.js

@@ -1,5 +1,5 @@
 /*
- * JavaScript Templates 1.0.1
+ * JavaScript Templates 1.0.2
  * https://github.com/blueimp/JavaScript-Templates
  *
  * Copyright 2011, Sebastian Tschan
@@ -45,7 +45,7 @@
             if (p3 === "=") {
                 return "'+_e(" + p4 + ")+'";
             }
-            return "'+" + p4 + "+'";
+            return "'+(" + p4 + "||'')+'";
         }
         if (p5) { // evaluation start tag: {%
             return "';";
@@ -63,7 +63,7 @@
         "\x00": ""
     };
     tmpl.encode = function (s) {
-        return String(s).replace(
+        return String(s || "").replace(
             tmpl.encReg,
             function (c) {
                 return tmpl.encMap[c];
@@ -72,7 +72,7 @@
     };
     tmpl.arg = "o";
     tmpl.helper = ",_t=arguments.callee.tmpl,_e=_t.encode" +
-        ",print=function(s,e){_s+=e&&s||_e(s);}" +
+        ",print=function(s,e){_s+=e&&(s||'')||_e(s);}" +
         ",include=function(s,d){_s+=_t(s,d);}";
     if (typeof define === "function" && define.amd) {
         // Register as an AMD module: