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| 1 | +import { html, LitElement } from "lit"; |
| 2 | +import { customElement, state } from "lit/decorators.js"; |
| 3 | +import type { User } from "jsonplaceholder-types/types/user"; |
| 4 | +import type { Post } from "jsonplaceholder-types/types/post"; |
| 5 | + |
| 6 | +@customElement("app-root") |
| 7 | +export class AppElement extends LitElement { |
| 8 | + static readonly #urlBase = "https://jsonplaceholder.typicode.com"; |
| 9 | + |
| 10 | + @state() |
| 11 | + private accessor _users: User[] | undefined; |
| 12 | + @state() |
| 13 | + private accessor _loadingUsers = false; |
| 14 | + |
| 15 | + @state() |
| 16 | + private accessor _selectedUserId: number | undefined; |
| 17 | + |
| 18 | + @state() |
| 19 | + private accessor _posts: Post[] | undefined; |
| 20 | + @state() |
| 21 | + private accessor _loadingPosts = false; |
| 22 | + |
| 23 | + #usersController?: AbortController; |
| 24 | + #postsController?: AbortController; |
| 25 | + |
| 26 | + override connectedCallback() { |
| 27 | + super.connectedCallback(); |
| 28 | + this.#fetchUsers(); |
| 29 | + } |
| 30 | + |
| 31 | + override disconnectedCallback() { |
| 32 | + super.disconnectedCallback(); |
| 33 | + this.#usersController?.abort(); |
| 34 | + this.#postsController?.abort(); |
| 35 | + } |
| 36 | + |
| 37 | + override updated(changed: Map<string, unknown>) { |
| 38 | + if (changed.has("_selectedUserId")) { |
| 39 | + this.#fetchPosts(); |
| 40 | + } |
| 41 | + } |
| 42 | + |
| 43 | + async #fetchUsers() { |
| 44 | + this._loadingUsers = true; |
| 45 | + this.#usersController?.abort(); |
| 46 | + this.#usersController = new AbortController(); |
| 47 | + try { |
| 48 | + const res = await fetch( |
| 49 | + `${AppElement.#urlBase}/users`, |
| 50 | + { signal: this.#usersController.signal }, |
| 51 | + ); |
| 52 | + this._users = await res.json(); |
| 53 | + } catch (err) { |
| 54 | + if (!(err instanceof DOMException && err.name === "AbortError")) { |
| 55 | + throw err; |
| 56 | + } |
| 57 | + } finally { |
| 58 | + this._loadingUsers = false; |
| 59 | + } |
| 60 | + } |
| 61 | + |
| 62 | + async #fetchPosts() { |
| 63 | + if (this._selectedUserId === undefined) { |
| 64 | + this._posts = undefined; |
| 65 | + return; |
| 66 | + } |
| 67 | + this._loadingPosts = true; |
| 68 | + this.#postsController?.abort(); |
| 69 | + this.#postsController = new AbortController(); |
| 70 | + try { |
| 71 | + const res = await fetch( |
| 72 | + `${AppElement.#urlBase}/posts?userId=${this._selectedUserId}`, |
| 73 | + { signal: this.#postsController.signal }, |
| 74 | + ); |
| 75 | + this._posts = await res.json(); |
| 76 | + } catch (err) { |
| 77 | + if (!(err instanceof DOMException && err.name === "AbortError")) { |
| 78 | + throw err; |
| 79 | + } |
| 80 | + } finally { |
| 81 | + this._loadingPosts = false; |
| 82 | + } |
| 83 | + } |
| 84 | + |
| 85 | + #onUserChange(e: Event) { |
| 86 | + const value = (e.target as HTMLSelectElement).value; |
| 87 | + this._selectedUserId = value ? Number(value) : undefined; |
| 88 | + } |
| 89 | + |
| 90 | + override render() { |
| 91 | + return html` |
| 92 | + <h1>Buildless Lit 3 app</h1> |
| 93 | + ${this._users |
| 94 | + ? html` |
| 95 | + <label> |
| 96 | + Select User: |
| 97 | + <select @change="${this.#onUserChange}"> |
| 98 | + <option ?selected="${this._selectedUserId === |
| 99 | + undefined}" hidden></option> |
| 100 | + ${this._users.map( |
| 101 | + (user) => |
| 102 | + html` |
| 103 | + <option |
| 104 | + value="${user.id}" |
| 105 | + ?selected="${user.id === this._selectedUserId}" |
| 106 | + > |
| 107 | + @${user.username}: ${user.name} |
| 108 | + </option> |
| 109 | + `, |
| 110 | + )} |
| 111 | + </select> |
| 112 | + </label> |
| 113 | + ` |
| 114 | + : this._loadingUsers |
| 115 | + ? html` |
| 116 | + <p>Loading Users...</p> |
| 117 | + ` |
| 118 | + : null} ${this._posts |
| 119 | + ? html` |
| 120 | + <ul> |
| 121 | + ${this._posts.map( |
| 122 | + (post) => |
| 123 | + html` |
| 124 | + <li>${post.title}</li> |
| 125 | + `, |
| 126 | + )} |
| 127 | + </ul> |
| 128 | + ` |
| 129 | + : this._loadingPosts |
| 130 | + ? html` |
| 131 | + <p>Loading Posts...</p> |
| 132 | + ` |
| 133 | + : this._users |
| 134 | + ? html` |
| 135 | + <p>Select User to view posts</p> |
| 136 | + ` |
| 137 | + : null} |
| 138 | + <p> |
| 139 | + Data Source: |
| 140 | + <a href="https://jsonplaceholder.typicode.com/" target="_blank"> |
| 141 | + JSONPlaceholder |
| 142 | + </a> |
| 143 | + </p> |
| 144 | + `; |
| 145 | + } |
| 146 | +} |
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