Author image Laurent Dami
and 1 contributors


Alien::GvaScript::Autocompleter - autocompletion on form input fields


In Javascript :

  var autocompleter1 = new GvaScript.Autocompleter(
      {minimumChars : 2, 
       strict       : true, 
       onBind       : doSomething,
       onLeave      : doSomethingElse}  );

  var autoCompleter2 = new GvaScript.Autocompleter(
        ["foo", "bar", ...], options);

  var autoCompleter3 = new GvaScript.Autocompleter(
        [{label: "foo", value: "f", otherValue: 123},
         {label: "bar", value: "b", otherValue: 456}, ...], options);

  var autoCompleter4 = new GvaScript.Autocompleter(
        myCompletionFunction, options);

Then, in HTML :

  <input onfocus="autoCompleter1.autocomplete(this)">


Component designed both as an "autocompleter" (anticipating further key events by users) and as a replacement for HTML SELECT form items.

An autocompleter instance encapsulates a datasource (which may be an inline object, a callback function or an Ajax request), together with some behavioral options (detailed below). That autocompleter may then be bound to one or several input fields in a form (but only one at a time), and will take care of capturing user input, navigating in the suggestion list, and filling the field with the chosen value.

An event model is associated with the autocompleter, so that client code can insert hooks to various steps of the autocompletion behaviour.

The list of suggestions may contain arbitrary HTML, including rich formatting options.


When the input field gets focus, the autocompleter starts listening for key events. As soon as minimumChars have been typed, or if the user presses the DOWN arrow key, the autocompleter gets a list of suggestions from the datasource, and displays them in a dropdown list.

The dropdown list can be navigated through arrow keys. Selecting a suggestion in the list is done either by a click, or by pressing the RETURN key (this is handled by the Alien::GvaScript::ChoiceList component of GvaScript). Then the value of that suggestion fills the input field value, dependent fields (if any) are updated, and the onLegalValue event is triggered.

A number of variations on this behaviour may be controlled by the options described below.


  var myAutocompleter = new GvaScript.Autocompleter(datasource, options);



A datasource may be

a plain string

The string is taken as a base URL. Whenever a suggestion list is needed, the autocompleter will send an Ajax requests to that URL, concatenated with the current value in the associated field. So for example if we have

  var ac = new GvaScript.Autocompleter("/myapp/completion?search=");
  <input name="someInput" onfocus="ac.complete(this)">

and user has typed ab in the input field, then an Ajax request will be sent to /myapp/completion?search=ab.

The server should return a JSON array, in the format explained below.

a callback function

That function will be called, with the current value of the field as single argument.

an array

The array is taken as in-memory datasource. The returned suggestion list is either the complete array (when options.ignorePrefix is true) or just the list of items that are prefixed by the current value of the field. See also options.caseSensitive.

an object (JSONP)

Useful when accessing data on a different domain via JSONP services.

  Ex :   { json_url: '',
           json_list: 'ResultSet/Result' }

The object should hold details of the JSONP service to be called.

json_url : url to call with placeholders (?1, ?2) for value to look for and callback method respectively.

json_list : path to the list in the json response

Format of suggestions returned by datasources

Datasources should return a list of suggestions in the form of a Javascript array (in case of Ajax requests, the response should be a JSON body containing a single array).

For each suggestion in the array, the autocompleter needs a label (an HTML fragment to display in suggestion dropdown lists) and a value (a plain string to put into the text field when the suggestion is selected). So each suggestion may be either

a plain string

this string will be used both as label and as value.

an inline object

this object is supposed to have a label property and a value property. Actually, these are the default names for the properties; they can be changed in the constructor options.

The label property may contain rich HTML, i.e. including formatting tags.


The options to construct an autocompleter object are :


How many characters are needed before trying to find suggestions.


Name of the field that contains the HTML to display (default is label).


Name of the field that contains the value to put in input element (default is value).


Boolean value; toggles whether suggestions are displayed automatically when available (true by default). If false, suggestions are only displayed when the ARROW_DOWN key is pressed.


How many milliseconds to wait after a keypress before displaying suggestions. Default is 200.


If true (the default), the current suggestion will be automatically inserted into the input element.


Maximum height for the suggestion DIV (in pixels). Default is 200.


Minimum width for the suggestion DIV (in pixels) Default is 200.


Offset (in pixels) from the left border of the input element to the left border of the suggestion DIV. Default is 0.


If this option is true and the user leaves the field with an illegal value (not in the suggestion list), the field is marked with a red background. Default is false.


If this option is defined and false, the field is marked with a red background when left with an empty value. Default is true.


If true, and if the datasource is a Javascript array, then that whole array is always displayed as suggestions, whatever may be typed in the input field (so the field behaves more or less like a SELECT). Default is false.


This option only applies if the datasource is a Javascript array and if ignorePrefix is false. If true (the default), filtering of the datasource array from the current value of the input field will be case-sensitive.


Which color to put in the background when a "strict" field contains an illegal value (default is red).


How many items to skip when hitting the PAGE_UP or PAGE_DOWN keys. Default is 5


See the ChoiceList documentation.


See the ChoiceList documentation.


Classes that will be assigned at various stages to autocompleter DOM elements . Possible classes are


Class added to the input or textarea field while an Ajax request is pending. Default is AC_loading, a class that displays an Ajax-loading icon.

Class for the dropdown div that displays the autocompletion choices. Default is AC_dropdown.


Class for displaying warning messages. Default is AC_message.


Other parameters to be added in the Ajax query for autocompletion. Can be either an array or an already encoded string (see Ajax.Options in prototype.js). [TODO: should be camelCase to be consistent with other options; check dependencies in DMWeb].

  var ac =  new GvaScript.Autocompleter(url, {
              dependentFields : {
                foo : "firstname",
                bar : "lastname",
                id  : "id"
              } } );

Inline object that specifies dependencies between the field controlled by the autocompleter, and other fields in the same form. When leaving the autocompleted field (onBlur), the dependent fields will be updated automatically. This only works for autocompleters in strict mode.

Each key in the inline object specifies the name of a field related to the autocompleted field. If field names are in dotted notation, then the related field is taken as a path relative to the autocompleted field : so for example if the autocompleted field has name some.very.3.long.2.path, then the foo entry in dependentFields will refer to field

The corresponding value (in our example above: firstname) is the name of a property to extract from the choice member that validated the current input. However, the autocompleted field may also contain an empty value (in which case the related fields are also emptied), or an illegal value (in which case the related fields are filled with string ILLEGAL_***, where *** is the key from the inline object).

If the choice member is not an object, but just a string, then that string is copied to the dependent field, therefore ignoring the hash value (firstname in our example).

As a special case, if the hash value is an empty string, then the dependent field is emptied, ignoring whatever information may be in the choice element.

The dependent fields structure might also be specified as an HTML attribute ac:dependentFields, instead of an option to the Javascript object :

  <input name="some.very.3.long.2.path"
         ac:dependentFields="{foo:'firstname',bar:'lastname',id:'id'}" />
  <input type="hidden"
         name="" />



Returns an event handler to be bound to the onfocus event on an input field, i.e.

  <input name="someInput" onfocus="myAutoCompleter.complete(this)">

The autocompleter will automatically register onblur, onclick and onkeydown handlers on the same field, so avoid setting your own, which may cause unpredictable interactions. However the autocompleter has its own event model to which you can bind your handling code (see the EVENTS section below).


Permanently detaches the input field from the autocompleter object (i.e. removes onblur and onkeypress handlers that were previously set by the first invocation of the autocomplete method).


Displays the given message within a newly created dropdown DIV under the input field. Used internally to warn for example about illegal values.


For a general explanation on registering handlers for GvaScript events, see the event documentation. In short, you can register handlers either on the HTML input element, as in

  <input name="someInput" onfocus = "myAutoCompleter.complete(this)"
                          onBind  = "bindHandler(this, event)"
                          onLeave = "leaveHandler">

or on the javascript object, as in

   myAutocompleter.onBind = function(event) {
        bindHandler(, event)
   myAutocompleter.onLeave = leaveHandler;

Below is the list of events generated by autocompleter objects.


This event is triggered whenever the autocompleter object becomes associated with an input field; typically this occurs when the input field receives focus and then calls the "autocomplete" method.


This event is triggered whenever the autocompleter object cuts the association with an input field; typically this occurs when the input field loses focus.

If in strict mode, the autocompleter object will also check if the final value is legal or illegal with respect to the list of available choices. This may require an additional Ajax call, so the onLeave event may be triggered before the onLegalValue or onIllegalValue events.


[OBSOLETE; use onLegalValue or onIllegalValue instead]

This event is triggered whenever the user has chosen an item in the displayed suggestion list. The event handler may use event.index to know the index of the selected choice.


This event is triggered when the autocompleter is in strict mode, the input field has just been left (onBlur event), and the autocompleter was able to verify that the current input value belongs to the list of available choices.

The event contains a value property (current value in the input element), and a choice property (member of the choices array that matches the current value). The controller property is null because the event may occur after the autocompleter object has been detached from the input field and has been perhaps already bound to another field, so interacting with the autocompleter from the event handler would lead to inconsistencies.


This event is triggered when the autocompleter is in strict mode, the input field has just been left (onBlur event), and the autocompleter was not able to verify that the current input value belongs to the list of available choices.

The event only contains a value property (current value in the input element). The controller property is null (same reasons as onLegalValue above).

return true in onIllegalValue handler to override the illegal behavior; i.e. coloring the input in red and invalidating the dependentFields.


This event is triggered when a choice in the dropdown list of choices is highlighted. The event handler may use event.index to know the index of the highlighted choice.


This event is triggered when the user presses the ESCAPE key.