htmx.org/dist/ext/response-targets.js

(function(){

    /** @type {import("../htmx").HtmxInternalApi} */
    var api;

    var attrPrefix = 'hx-target-';

    // IE11 doesn't support string.startsWith
    function startsWith(str, prefix) {
        return str.substring(0, prefix.length) === prefix
    }

    /**
     * @param {HTMLElement} elt
     * @param {number} respCode
     * @returns {HTMLElement | null}
     */
    function getRespCodeTarget(elt, respCodeNumber) {
        if (!elt || !respCodeNumber) return null;

        var respCode = respCodeNumber.toString();

        // '*' is the original syntax, as the obvious character for a wildcard.
        // The 'x' alternative was added for maximum compatibility with HTML
        // templating engines, due to ambiguity around which characters are
        // supported in HTML attributes.
        //
        // Start with the most specific possible attribute and generalize from
        // there.
        var attrPossibilities = [
            respCode,

            respCode.substr(0, 2) + '*',
            respCode.substr(0, 2) + 'x',

            respCode.substr(0, 1) + '*',
            respCode.substr(0, 1) + 'x',
            respCode.substr(0, 1) + '**',
            respCode.substr(0, 1) + 'xx',

            '*',
            'x',
            '***',
            'xxx',
        ];
        if (startsWith(respCode, '4') || startsWith(respCode, '5')) {
            attrPossibilities.push('error');
        }

        for (var i = 0; i < attrPossibilities.length; i++) {
            var attr = attrPrefix + attrPossibilities[i];
            var attrValue = api.getClosestAttributeValue(elt, attr);
            if (attrValue) {
                if (attrValue === "this") {
                    return api.findThisElement(elt, attr);
                } else {
                    return api.querySelectorExt(elt, attrValue);
                }
            }
        }
        
        return null;
    }

    /** @param {Event} evt */
    function handleErrorFlag(evt) {
        if (evt.detail.isError) {
            if (htmx.config.responseTargetUnsetsError) {
                evt.detail.isError = false;
            }
        } else if (htmx.config.responseTargetSetsError) {
            evt.detail.isError = true;
        }
    }

    htmx.defineExtension('response-targets', {

        /** @param {import("../htmx").HtmxInternalApi} apiRef */
        init: function (apiRef) {
            api = apiRef;

            if (htmx.config.responseTargetUnsetsError === undefined) {
                htmx.config.responseTargetUnsetsError = true;
            }
            if (htmx.config.responseTargetSetsError === undefined) {
                htmx.config.responseTargetSetsError = false;
            }
            if (htmx.config.responseTargetPrefersExisting === undefined) {
                htmx.config.responseTargetPrefersExisting = false;
            }
            if (htmx.config.responseTargetPrefersRetargetHeader === undefined) {
                htmx.config.responseTargetPrefersRetargetHeader = true;
            }
        },

        /**
         * @param {string} name
         * @param {Event} evt
         */
        onEvent: function (name, evt) {
            if (name === "htmx:beforeSwap"    &&
                evt.detail.xhr                &&
                evt.detail.xhr.status !== 200) {
                if (evt.detail.target) {
                    if (htmx.config.responseTargetPrefersExisting) {
                        evt.detail.shouldSwap = true;
                        handleErrorFlag(evt);
                        return true;
                    }
                    if (htmx.config.responseTargetPrefersRetargetHeader &&
                        evt.detail.xhr.getAllResponseHeaders().match(/HX-Retarget:/i)) {
                        evt.detail.shouldSwap = true;
                        handleErrorFlag(evt);
                        return true;
                    }
                }
                if (!evt.detail.requestConfig) {
                    return true;
                }
                var target = getRespCodeTarget(evt.detail.requestConfig.elt, evt.detail.xhr.status);
                if (target) {
                    handleErrorFlag(evt);
                    evt.detail.shouldSwap = true;
                    evt.detail.target = target;
                }
                return true;
            }
        }
    });
})();