@wordpress/hooks/build-module/createAddHook.js

WordPress hooks library.

/**
 * Internal dependencies
 */
import validateNamespace from './validateNamespace';
import validateHookName from './validateHookName';

/**
 *
 * Adds the hook to the appropriate hooks container.
 */

/**
 * Returns a function which, when invoked, will add a hook.
 *
 * @param hooks    Hooks instance.
 * @param storeKey
 *
 * @return  Function that adds a new hook.
 */
function createAddHook(hooks, storeKey) {
  return function addHook(hookName, namespace, callback, priority = 10) {
    const hooksStore = hooks[storeKey];
    if (!validateHookName(hookName)) {
      return;
    }
    if (!validateNamespace(namespace)) {
      return;
    }
    if ('function' !== typeof callback) {
      // eslint-disable-next-line no-console
      console.error('The hook callback must be a function.');
      return;
    }

    // Validate numeric priority
    if ('number' !== typeof priority) {
      // eslint-disable-next-line no-console
      console.error('If specified, the hook priority must be a number.');
      return;
    }
    const handler = {
      callback,
      priority,
      namespace
    };
    if (hooksStore[hookName]) {
      // Find the correct insert index of the new hook.
      const handlers = hooksStore[hookName].handlers;
      let i;
      for (i = handlers.length; i > 0; i--) {
        if (priority >= handlers[i - 1].priority) {
          break;
        }
      }
      if (i === handlers.length) {
        // If append, operate via direct assignment.
        handlers[i] = handler;
      } else {
        // Otherwise, insert before index via splice.
        handlers.splice(i, 0, handler);
      }

      // We may also be currently executing this hook.  If the callback
      // we're adding would come after the current callback, there's no
      // problem; otherwise we need to increase the execution index of
      // any other runs by 1 to account for the added element.
      hooksStore.__current.forEach(hookInfo => {
        if (hookInfo.name === hookName && hookInfo.currentIndex >= i) {
          hookInfo.currentIndex++;
        }
      });
    } else {
      // This is the first hook of its type.
      hooksStore[hookName] = {
        handlers: [handler],
        runs: 0
      };
    }
    if (hookName !== 'hookAdded') {
      hooks.doAction('hookAdded', hookName, namespace, callback, priority);
    }
  };
}
export default createAddHook;
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