How to Access JSF Component IDs in JavaScript?

Knowing the Id of a JSF Component for Usage in Javascript

In Javascript, the getElementById function can be leveraged to access a component. However, since JSF dynamically generates component IDs, obtaining the component's ID is crucial. This article explores ways to retrieve the component's ID for use in Javascript.

Consider the following scenario where we want to access the inputText component via Javascript code:

<h:inputText>

function myFunc() {
  // Get the inputText component's contents
  alert("Your email address is: " + document.getElementById("emailAddress").value);
}

Using Document.getElementById with Generated HTML DOM Element

The generated HTML DOM element has a structure that differs from the ID you specify in JSF. Inspecting the generated code will reveal the assigned ID. For instance, the inputText in the above example might have been rendered as:

<input type="text">

where "j_id0:emailAddress" represents the actual ID in the HTML DOM generated by JSF. Therefore, to accurately reference the component in Javascript, use the generated ID instead of the specified ID.

Setting a Fixed ID for JSF NamingContainers

Alternatively, you can assign a fixed ID to JSF NamingContainer components, such as forms, to prevent JSF from auto-generating IDs. For instance:

<h:form>

With this setup, the form ID will be fixed as "formId," and the inputText ID will be "formId:emailAddress," which you can now use directly in Javascript.

Using #{Component.clientId} with Binding

A more advanced technique involves using the #{component.clientId} expression together with a component binding. For example:

<h:inputText binding="#{emailAddress}" ... />

var input = document.getElementById('#{emailAddress.clientId}');

Update:

Direct Usage of #{component.clientId}

The blog article mentioned in the problem relates directly to #{component} references, which refer to the current component where the EL expression is evaluated. To obtain the component's ID, use the following syntax:

var input = document.getElementById('#{component.clientId}');

Passing HTML DOM Element as "this" Reference

Another approach is to pass the generated HTML DOM element as the "this" reference to a function, allowing you to directly access the component's properties within the function.

<h:inputText onclick="show(this)" />

function show(input) {
  alert(input.value);
}

Using jQuery and Event Delegation

jQuery offers an even more advanced option by using event delegation and a style class to abstract the components.

<h:inputText styleClass="someMarkerClass" />

$(document).on("click", ".someMarkerClass", function() {
  var $input = $(this);
  alert($input.val());
});

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