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| 1 | +/* |
| 2 | + * Copyright (c) 2025, salesforce.com, inc. |
| 3 | + * All rights reserved. |
| 4 | + * SPDX-License-Identifier: MIT |
| 5 | + * For full license text, see the LICENSE file in the repo root or https://opensource.org/licenses/MIT |
| 6 | + */ |
| 7 | +import { isUndefined } from '@lwc/shared'; |
| 8 | +import { EmptyObject } from '../utils'; |
| 9 | +import { invokeEventListener } from '../invoker'; |
| 10 | +import { logError } from '../../shared/logger'; |
| 11 | +import type { VM } from '../vm'; |
| 12 | +import type { VBaseElement } from '../vnodes'; |
| 13 | +import type { RendererAPI } from '../renderer'; |
| 14 | + |
| 15 | +export function patchDynamicEventListeners( |
| 16 | + oldVnode: VBaseElement | null, |
| 17 | + vnode: VBaseElement, |
| 18 | + renderer: RendererAPI, |
| 19 | + owner: VM |
| 20 | +) { |
| 21 | + const { |
| 22 | + elm, |
| 23 | + data: { dynamicOn, dynamicOnRaw }, |
| 24 | + sel, |
| 25 | + } = vnode; |
| 26 | + |
| 27 | + // dynamicOn : A cloned version of the object passed to lwc:on, with null prototype and only its own enumerable properties. |
| 28 | + const oldDynamicOn = oldVnode?.data?.dynamicOn ?? EmptyObject; |
| 29 | + const newDynamicOn = dynamicOn ?? EmptyObject; |
| 30 | + |
| 31 | + // dynamicOnRaw : object passed to lwc:on |
| 32 | + // Compare dynamicOnRaw to check if same object is passed to lwc:on |
| 33 | + const isObjectSame = oldVnode?.data?.dynamicOnRaw === dynamicOnRaw; |
| 34 | + |
| 35 | + const { addEventListener, removeEventListener } = renderer; |
| 36 | + const attachedEventListeners = getAttachedEventListeners(owner, elm!); |
| 37 | + |
| 38 | + // Properties that are present in 'oldDynamicOn' but not in 'newDynamicOn' |
| 39 | + for (const eventType in oldDynamicOn) { |
| 40 | + if (!(eventType in newDynamicOn)) { |
| 41 | + // log error if same object is passed |
| 42 | + if (isObjectSame && process.env.NODE_ENV !== 'production') { |
| 43 | + logError( |
| 44 | + `Detected mutation of property '${eventType}' in the object passed to lwc:on for <${sel}>. Reusing the same object with modified properties is prohibited. Please pass a new object instead.`, |
| 45 | + owner |
| 46 | + ); |
| 47 | + } |
| 48 | + |
| 49 | + // Remove listeners that were attached previously but don't have a corresponding property in `newDynamicOn` |
| 50 | + const attachedEventListener = attachedEventListeners[eventType]; |
| 51 | + removeEventListener(elm, eventType, attachedEventListener!); |
| 52 | + attachedEventListeners[eventType] = undefined; |
| 53 | + } |
| 54 | + } |
| 55 | + |
| 56 | + // Ensure that the event listeners that are attached match what is present in `newDynamicOn` |
| 57 | + for (const eventType in newDynamicOn) { |
| 58 | + const typeExistsInOld = eventType in oldDynamicOn; |
| 59 | + const newCallback = newDynamicOn[eventType]; |
| 60 | + |
| 61 | + // Skip if callback hasn't changed |
| 62 | + if (typeExistsInOld && oldDynamicOn[eventType] === newCallback) { |
| 63 | + continue; |
| 64 | + } |
| 65 | + |
| 66 | + // log error if same object is passed |
| 67 | + if (isObjectSame && process.env.NODE_ENV !== 'production') { |
| 68 | + logError( |
| 69 | + `Detected mutation of property '${eventType}' in the object passed to lwc:on for <${sel}>. Reusing the same object with modified properties is prohibited. Please pass a new object instead.`, |
| 70 | + owner |
| 71 | + ); |
| 72 | + } |
| 73 | + |
| 74 | + // Remove listener that was attached previously |
| 75 | + if (typeExistsInOld) { |
| 76 | + const attachedEventListener = attachedEventListeners[eventType]; |
| 77 | + removeEventListener(elm, eventType, attachedEventListener!); |
| 78 | + } |
| 79 | + |
| 80 | + // Bind new callback to owner component and add it as listener to element |
| 81 | + const newBoundEventListener = bindEventListener(owner, newCallback); |
| 82 | + addEventListener(elm, eventType, newBoundEventListener); |
| 83 | + |
| 84 | + // Store the newly added eventListener |
| 85 | + attachedEventListeners[eventType] = newBoundEventListener; |
| 86 | + } |
| 87 | +} |
| 88 | + |
| 89 | +function getAttachedEventListeners( |
| 90 | + vm: VM, |
| 91 | + elm: Element |
| 92 | +): Record<string, EventListener | undefined> { |
| 93 | + let attachedEventListeners = vm.attachedEventListeners.get(elm); |
| 94 | + if (isUndefined(attachedEventListeners)) { |
| 95 | + attachedEventListeners = {}; |
| 96 | + vm.attachedEventListeners.set(elm, attachedEventListeners); |
| 97 | + } |
| 98 | + return attachedEventListeners; |
| 99 | +} |
| 100 | + |
| 101 | +function bindEventListener(vm: VM, fn: EventListener): EventListener { |
| 102 | + return function (event: Event) { |
| 103 | + invokeEventListener(vm, fn, vm.component, event); |
| 104 | + }; |
| 105 | +} |
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