Changes between Version 15 and Version 16 of Coding_Conventions

Timestamp:

Mar 5, 2012, 12:31:57 AM (12 years ago)

Author:

historic_bruno

Comment:

Some info about JS undefined vs. null

Coding_Conventions

@@ -249 +249 @@
 }}}
 
+ * To test if a property or variable is undefined, use explicit type+value equality (`===`), instead of value equality (`==`) or `typeof()`:
+{{{
+#!js
+if (someObject.foo === undefined)
+  // foo is not defined
+else
+  // foo is defined
+}}}
+ * In general you don't want to explicitly check for `null` which has a distinct, often misunderstood, meaning from `undefined`. A few parts of the engine return a `null` object reference (for example, the component system when a component is not available for the specified entity, or the GUI when a requested object was not found), you can check for valid object references easily:
+{{{
+#!js
+if (!cmpFoo)
+  // Oh it's not a valid component, don't use it
+else
+  // It is a valid component, we can use it
+}}}
+
 == XML ==