Add documentation

2 files changed, 46 insertions, 11 deletions

diff --git a/README.md b/README.md
index 80ae96b..d5f59b9 100644
--- a/README.md
+++ b/README.md
@@ -58,29 +58,51 @@ be used to ensure that a function is only applied once to an element.
 
 ## Usage
 
-### `.once()`
+### `.once(id)`
 
 Filter elements by whether they have not yet been processed.
 
+#### Parameters
+
+* `id` *string* (optional) The data id used to determine whether the given elements have
+already been processed or not. Default: `once`
+
+#### Returns
+
+jQuery element collection of elements that have now run once by the given id.
+
+#### Example
+
 ``` javascript
-$('div.calendar').once('calendar').each(function() {
-  // This function is only executed once for each div, even if this
-  // code segment is executed repeatedly.
-});
 $('div.calendar').once('calendar').click(function() {
   // .once('calendar') filters out all elements which already have been
-  // filtered with once(), and the elements that haven't been filtered
+  // filtered with once('calendar'), and the elements that haven't been filtered
   // yet remain. The previous set of elements can be restored with
   // .end().
 });
+$('div.calendar').once().each(function() {
+  // This function is only executed once for each div, even if this
+  // code segment is executed repeatedly. Keyed by "once".
+});
 ```
 
 
-### `.findOnce()`
+### `.findOnce(id)`
 
 After `.once()` is used and you need to retrieve all elements that have already
 been executed with `.once()`, you can use the `.findOnce() function:
 
+#### Parameters
+
+* `id` *string* The data id used to determine whether the given elements have
+already been processed or not.
+
+#### Returns
+
+jQuery element collection of elements that have been run once.
+
+#### Example
+
 ``` javascript
 $('div.calendar').findOnce('calendar').each(function() {
   // This function is called for each element that was already called "once"
@@ -88,10 +110,23 @@ $('div.calendar').findOnce('calendar').each(function() {
 });
 ```
 
-### `.removeOnce()`
+### `.removeOnce(id)`
+
+A required string representing the name of the data id which should be used when
+filtering the elements. This only filters elements that have already been processed by
+the once function. The id should be the same id that was originally passed to the
+`once()` function.
+
+#### Parameters
+
+* `id` *string* The data id used to determine whether the given elements have
+already been processed or not.
+
+#### Returns
+
+jQuery element collection of elements that now have their once data removed.
 
-It is possible to remove the `.once()` data, and iterate through each element
-whose once state is removed:
+#### Example
 
 ``` javascript
 $('div.calendar').removeOnce('calendar').each(function() {
diff --git a/jquery.once.js b/jquery.once.js
index c8e606c..a13b9f8 100644
--- a/jquery.once.js
+++ b/jquery.once.js
@@ -53,7 +53,7 @@
   $.fn.once = function (id) {
     id = id || "once";
     if (typeof id !== "string") {
-      throw new Error("jQuery.once() parameter MUST be a string");
+      throw new Error("jQuery.once() parameter must be a string");
     }
     // Build the name for the data identifier. Generate a new unique id if the
     // id parameter is not provided.