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[FEATURE] Implement
on modifier. (#17960)
[FEATURE] Implement `on` modifier.
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,262 @@ | ||
| import { assert } from '@ember/debug'; | ||
| import { DEBUG } from '@glimmer/env'; | ||
| import { Opaque, Simple } from '@glimmer/interfaces'; | ||
| import { Tag } from '@glimmer/reference'; | ||
| import { Arguments, CapturedArguments, ModifierManager } from '@glimmer/runtime'; | ||
| import { Destroyable } from '@glimmer/util'; | ||
| import buildUntouchableThis from '../utils/untouchable-this'; | ||
|
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| const untouchableContext = buildUntouchableThis('`on` modifier'); | ||
|
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| /* | ||
| Internet Explorer 11 does not support `once` and also does not support | ||
| passing `eventOptions`. In some situations it then throws a weird script | ||
| error, like: | ||
| ``` | ||
| Could not complete the operation due to error 80020101 | ||
| ``` | ||
| This flag determines, whether `{ once: true }` and thus also event options in | ||
| general are supported. | ||
| */ | ||
| const SUPPORTS_EVENT_OPTIONS = (() => { | ||
| try { | ||
| const div = document.createElement('div'); | ||
| let counter = 0; | ||
| div.addEventListener('click', () => counter++, { once: true }); | ||
|
|
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| let event; | ||
| if (typeof Event === 'function') { | ||
| event = new Event('click'); | ||
| } else { | ||
| event = document.createEvent('Event'); | ||
| event.initEvent('click', true, true); | ||
| } | ||
|
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| div.dispatchEvent(event); | ||
| div.dispatchEvent(event); | ||
|
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| return counter === 1; | ||
| } catch (error) { | ||
| return false; | ||
| } | ||
| })(); | ||
|
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| export class OnModifierState { | ||
| public tag: Tag; | ||
| public element: Element; | ||
| public args: CapturedArguments; | ||
| public eventName!: string; | ||
| public callback!: EventListener; | ||
| private userProvidedCallback!: EventListener; | ||
| public once?: boolean; | ||
| public passive?: boolean; | ||
| public capture?: boolean; | ||
| public options?: AddEventListenerOptions; | ||
| public shouldUpdate = true; | ||
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| constructor(element: Element, args: CapturedArguments) { | ||
| this.element = element; | ||
| this.args = args; | ||
| this.tag = args.tag; | ||
| } | ||
|
|
||
| updateFromArgs() { | ||
| let { args } = this; | ||
|
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| let { once, passive, capture }: AddEventListenerOptions = args.named.value(); | ||
| if (once !== this.once) { | ||
| this.once = once; | ||
| this.shouldUpdate = true; | ||
| } | ||
|
|
||
| if (passive !== this.passive) { | ||
| this.passive = passive; | ||
| this.shouldUpdate = true; | ||
| } | ||
|
|
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| if (capture !== this.capture) { | ||
| this.capture = capture; | ||
| this.shouldUpdate = true; | ||
| } | ||
|
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| let options: AddEventListenerOptions; | ||
| if (once || passive || capture) { | ||
| options = this.options = { once, passive, capture }; | ||
| } else { | ||
| this.options = undefined; | ||
| } | ||
|
|
||
| assert( | ||
| 'You must pass a valid DOM event name as the first argument to the `on` modifier', | ||
| args.positional.at(0) !== undefined && typeof args.positional.at(0).value() === 'string' | ||
| ); | ||
| let eventName = args.positional.at(0).value() as string; | ||
| if (eventName !== this.eventName) { | ||
| this.eventName = eventName; | ||
| this.shouldUpdate = true; | ||
| } | ||
|
|
||
| assert( | ||
| 'You must pass a function as the second argument to the `on` modifier', | ||
| args.positional.at(1) !== undefined && typeof args.positional.at(1).value() === 'function' | ||
| ); | ||
| let userProvidedCallback = args.positional.at(1).value() as EventListener; | ||
| if (userProvidedCallback !== this.userProvidedCallback) { | ||
| this.userProvidedCallback = userProvidedCallback; | ||
| this.shouldUpdate = true; | ||
| } | ||
|
|
||
| assert( | ||
| `You can only pass two positional arguments (event name and callback) to the \`on\` modifier, but you provided ${ | ||
| args.positional.length | ||
| }. Consider using the \`fn\` helper to provide additional arguments to the \`on\` callback.`, | ||
| args.positional.length === 2 | ||
| ); | ||
|
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| let needsCustomCallback = | ||
| (SUPPORTS_EVENT_OPTIONS === false && once) /* needs manual once implementation */ || | ||
| (DEBUG && passive) /* needs passive enforcement */; | ||
|
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| if (this.shouldUpdate) { | ||
| if (needsCustomCallback) { | ||
| let callback = (this.callback = function(this: Element, event) { | ||
| if (DEBUG && passive) { | ||
| event.preventDefault = () => { | ||
| assert( | ||
| `You marked this listener as 'passive', meaning that you must not call 'event.preventDefault()': \n\n${userProvidedCallback}` | ||
| ); | ||
| }; | ||
| } | ||
|
|
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| if (!SUPPORTS_EVENT_OPTIONS && once) { | ||
| removeEventListener(this, eventName, callback, options); | ||
| } | ||
| return userProvidedCallback.call(untouchableContext, event); | ||
| }); | ||
| } else if (DEBUG) { | ||
| // prevent the callback from being bound to the element | ||
| this.callback = userProvidedCallback.bind(untouchableContext); | ||
| } else { | ||
| this.callback = userProvidedCallback; | ||
| } | ||
| } | ||
| } | ||
|
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| destroy() { | ||
| let { element, eventName, callback, options } = this; | ||
|
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| removeEventListener(element, eventName, callback, options); | ||
| } | ||
| } | ||
|
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| let adds = 0; | ||
| let removes = 0; | ||
|
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| function removeEventListener( | ||
| element: Element, | ||
| eventName: string, | ||
| callback: EventListener, | ||
| options?: AddEventListenerOptions | ||
| ): void { | ||
| removes++; | ||
|
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| if (SUPPORTS_EVENT_OPTIONS) { | ||
| // when options are supported, use them across the board | ||
| element.removeEventListener(eventName, callback, options); | ||
| } else if (options !== undefined && options.capture) { | ||
| // used only in the following case: | ||
| // | ||
| // `{ once: true | false, passive: true | false, capture: true } | ||
| // | ||
| // `once` is handled via a custom callback that removes after first | ||
| // invocation so we only care about capture here as a boolean | ||
| element.removeEventListener(eventName, callback, true); | ||
| } else { | ||
| // used only in the following cases: | ||
| // | ||
| // * where there is no options | ||
| // * `{ once: true | false, passive: true | false, capture: false } | ||
| element.removeEventListener(eventName, callback); | ||
| } | ||
| } | ||
|
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| function addEventListener( | ||
| element: Element, | ||
| eventName: string, | ||
| callback: EventListener, | ||
| options?: AddEventListenerOptions | ||
| ): void { | ||
| adds++; | ||
|
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| if (SUPPORTS_EVENT_OPTIONS) { | ||
| // when options are supported, use them across the board | ||
| element.addEventListener(eventName, callback, options); | ||
| } else if (options !== undefined && options.capture) { | ||
| // used only in the following case: | ||
| // | ||
| // `{ once: true | false, passive: true | false, capture: true } | ||
| // | ||
| // `once` is handled via a custom callback that removes after first | ||
| // invocation so we only care about capture here as a boolean | ||
| element.addEventListener(eventName, callback, true); | ||
| } else { | ||
| // used only in the following cases: | ||
| // | ||
| // * where there is no options | ||
| // * `{ once: true | false, passive: true | false, capture: false } | ||
| element.addEventListener(eventName, callback); | ||
| } | ||
| } | ||
|
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| export default class OnModifierManager implements ModifierManager<OnModifierState, Opaque> { | ||
| public SUPPORTS_EVENT_OPTIONS: boolean = SUPPORTS_EVENT_OPTIONS; | ||
|
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| get counters() { | ||
| return { adds, removes }; | ||
| } | ||
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| create(element: Simple.Element | Element, _state: Opaque, args: Arguments) { | ||
| const capturedArgs = args.capture(); | ||
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| return new OnModifierState(<Element>element, capturedArgs); | ||
| } | ||
|
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| getTag({ tag }: OnModifierState): Tag { | ||
| return tag; | ||
| } | ||
|
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| install(state: OnModifierState) { | ||
| state.updateFromArgs(); | ||
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| let { element, eventName, callback, options } = state; | ||
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| addEventListener(element, eventName, callback, options); | ||
|
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| state.shouldUpdate = false; | ||
| } | ||
|
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| update(state: OnModifierState) { | ||
| // stash prior state for el.removeEventListener | ||
| let { element, eventName, callback, options } = state; | ||
|
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| state.updateFromArgs(); | ||
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| if (!state.shouldUpdate) { | ||
| return; | ||
| } | ||
|
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| // use prior state values for removal | ||
| removeEventListener(element, eventName, callback, options); | ||
|
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| // read updated values from the state object | ||
| addEventListener(state.element, state.eventName, state.callback, state.options); | ||
|
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| state.shouldUpdate = false; | ||
| } | ||
|
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| getDestructor(state: Destroyable) { | ||
| return state; | ||
| } | ||
| } |
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39 changes: 39 additions & 0 deletions
39
packages/@ember/-internals/glimmer/lib/utils/untouchable-this.ts
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,39 @@ | ||
| import { HAS_NATIVE_PROXY } from '@ember/-internals/utils'; | ||
| import { assert } from '@ember/debug'; | ||
| import { DEBUG } from '@glimmer/env'; | ||
|
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| export default function buildUntouchableThis(source: string): null | object { | ||
| let context: null | object = null; | ||
| if (DEBUG && HAS_NATIVE_PROXY) { | ||
| let assertOnProperty = (property: string | number | symbol) => { | ||
| assert( | ||
| `You accessed \`this.${String( | ||
| property | ||
| )}\` from a function passed to the ${source}, but the function itself was not bound to a valid \`this\` context. Consider updating to usage of \`@action\`.` | ||
| ); | ||
| }; | ||
|
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| context = new Proxy( | ||
| {}, | ||
| { | ||
| get(_target: {}, property: string | symbol) { | ||
| assertOnProperty(property); | ||
| }, | ||
|
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| set(_target: {}, property: string | symbol) { | ||
| assertOnProperty(property); | ||
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| return false; | ||
| }, | ||
|
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| has(_target: {}, property: string | symbol) { | ||
| assertOnProperty(property); | ||
|
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| return false; | ||
| }, | ||
| } | ||
| ); | ||
| } | ||
|
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| return context; | ||
| } |
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