The response-targets Extension

This extension allows you to specify different target elements to be swapped when different HTTP response codes are received.

It uses attribute names in a form of hx-target-[CODE] where [CODE] is a numeric HTTP response code with the optional wildcard character at its end. You can also use hx-target-error, which handles both 4xx and 5xx response codes.

The value of each attribute can be:

• A CSS query selector of the element to target.
• this which indicates that the element that the hx-target attribute is on is the target.
• closest <CSS selector> which will find the closest parent ancestor that matches the given CSS selector (e.g. closest tr will target the closest table row to the element).
• find <CSS selector> which will find the first child descendant element that matches the given CSS selector.
• next <CSS selector> which will scan the DOM forward for the first element that matches the given CSS selector. (e.g. next .error will target the closest following sibling element with error class)
• previous <CSS selector> which will scan the DOM backwards for the first element that matches the given CSS selector. (e.g previous .error will target the closest previous sibling with error class)

#Install

<script src="https://unpkg.com/htmx.org/dist/ext/response-targets.js"></script>

#Configure (optional)

• When HX-Retarget response header is received it disables any lookup that would be performed by this extension but any responses with error status codes will be swapped (normally they would not be, even with target set via header) and internal error flag (isError) will be modified. You may change this and choose to ignore HX-Retarget header when hx-target-… is in place by setting a configuration flag htmx.config.responseTargetPrefersRetargetHeader to false (default is true). Note that this extension only performs a simple check whether the header is set and target exists. It is not extracting target’s value from the header but trusts it was set by HTMX core logic.

• Normally, any target which is already established by HTMX built-in functions or extensions called before will be overwritten if a matching hx-target-… tag is found. You may change it by using a configuration flag htmx.config.responseTargetPrefersExisting to true (default is false). This is kinky and risky option. It has a real-life applications similar to a skilled, full-stack tardigrade eating parentheses when no one is watching.

• isError flag on the detail member of an event associated with swapping the content with hx-target-[CODE] will be set to false when error response code is received. This is different from the default behavior. You may change this by setting a configuration flag htmx.config.responseTargetUnsetsError to false (default is true).

• isError flag on the detail member of an event associated with swapping the content with hx-target-[CODE] will be set to false when non-erroneous response code is received. This is no different from the default behavior. You may change this by setting a configuration flag htmx.config.responseTargetSetsError to true (default is false). This setting will not affect the response code 200 since it is not handled by this extension.

#Usage

Here is an example that targets a div for normal (200) response but another div for 404 (not found) response, and yet another for all 5xx response codes:

<div hx-ext="response-targets">
    <div id="response-div"></div>
    <button hx-post="/register"
            hx-target="#response-div"
            hx-target-5*="#serious-errors"
            hx-target-404="#not-found">
        Register!
    </button>
    <div id="serious-errors"></div>
    <div id="not-found"></div>
</div>

• The response from the /register URL will replace contents of the div with the id response-div when response code is 200 (OK).

• The response from the /register URL will replace contents of the div with the id serious-errors when response code begins with a digit 5 (server errors).

• The response from the /register URL will replace contents of the div with the id not-found when response code is 404 (Not Found).

Sometimes you may not want to handle 5xx and 4xx errors separately, in which case you can use hx-target-error:

<div hx-ext="response-targets">
    <div id="response-div"></div>
    <button hx-post="/register"
            hx-target="#response-div"
            hx-target-error="#any-errors">
        Register!
    </button>
    <div id="any-errors"></div>
</div>

2xx codes will be handled as in the previous example. However, when the response code is 5xx or 4xx, the response from /register will replace the contents of the div with the id any-errors.

#Wildcard resolution

When status response code does not match existing hx-target-[CODE] attribute name then its numeric part expressed as a string is trimmed with last character being replaced with the asterisk (*). This lookup process continues until the attribute is found or there are no more digits.

For example, if a browser receives 404 error code, the following attribute names will be looked up (in the given order):

• hx-target-404
• hx-target-40*
• hx-target-4*
• hx-target-*.

If you are using tools that do not support asterisks in HTML attributes, you may instead use the x character, e.g., hx-target-4xx.

#Notes

• hx-target-… is inherited and can be placed on a parent element.
• hx-target-… cannot be used to handle HTTP response code 200.
• hx-target-… will honor HX-Retarget by default and will prefer it over any calculated target but it can be changed by disabling the htmx.config.responseTargetPrefersRetargetHeader configuration option.
• To avoid surprises the hx-ext attribute used to enable this extension should be placed on a parent element containing elements with hx-target-… and hx-target attributes.

#See also

• hx-target, specifies the target element to be swapped