129 lines
3.2 KiB
Markdown
129 lines
3.2 KiB
Markdown
### TreeView
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Renders a tree view of a JSON object or array with collapsible content.
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Use object destructuring to set defaults for certain props.
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Use the value of the `toggled` prop to determine the initial state of the content (collapsed/expanded).
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Use the `setState()` hook to create the `isToggled` state variable and give it the value of the `toggled` prop initially.
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In the `render()` method, use a `<div>` to wrap the contents of the component and the `<span>` element, used to alter the component's `isToggled` state.
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Determine the appearance of the component, based on `isParentToggled`, `isToggled`, `name` and `Array.isArray()` on `data`.
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For each child in `data`, determine if it is an object or array and recursively render a sub-tree.
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Otherwise, render a `<p>` element with the appropriate style.
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```css
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.tree-element {
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margin: 0;
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position: relative;
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}
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div.tree-element:before {
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content: '';
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position: absolute;
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top: 24px;
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left: 1px;
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height: calc(100% - 48px);
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border-left: 1px solid gray;
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}
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.toggler {
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position: absolute;
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top: 10px;
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left: 0px;
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width: 0;
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height: 0;
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border-top: 4px solid transparent;
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border-bottom: 4px solid transparent;
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border-left: 5px solid gray;
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cursor: pointer;
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}
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.toggler.closed {
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transform: rotate(90deg);
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}
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.collapsed {
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display: none;
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}
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```
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```jsx
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function TreeView({
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data,
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toggled = true,
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name = null,
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isLast = true,
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isChildElement = false,
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isParentToggled = true
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}) {
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const [isToggled, setIsToggled] = React.useState(toggled);
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return (
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<div
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style={{ marginLeft: isChildElement ? 16 : 4 + "px" }}
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className={isParentToggled ? "tree-element" : "tree-element collapsed"}
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>
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<span
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className={isToggled ? "toggler" : "toggler closed"}
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onClick={() => setIsToggled(!isToggled)}
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/>
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{name ? <strong> {name}: </strong> : <span> </span>}
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{Array.isArray(data) ? "[" : "{"}
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{!isToggled && "..."}
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{Object.keys(data).map(
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(v, i, a) =>
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typeof data[v] == "object" ? (
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<TreeView
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data={data[v]}
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isLast={i === a.length - 1}
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name={Array.isArray(data) ? null : v}
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isChildElement
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isParentToggled={isParentToggled && isToggled}
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/>
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) : (
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<p
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style={{ marginLeft: 16 + "px" }}
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className={isToggled ? "tree-element" : "tree-element collapsed"}
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>
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{Array.isArray(data) ? "" : <strong>{v}: </strong>}
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{data[v]}
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{i === a.length - 1 ? "" : ","}
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</p>
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)
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)}
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{Array.isArray(data) ? "]" : "}"}
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{!isLast ? "," : ""}
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</div>
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);
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}
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```
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```jsx
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let data = {
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lorem: {
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ipsum: "dolor sit",
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amet: {
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consectetur: "adipiscing",
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elit: [
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"duis",
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"vitae",
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{
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semper: "orci"
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},
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{
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est: "sed ornare"
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},
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"etiam",
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["laoreet", "tincidunt"],
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["vestibulum", "ante"]
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]
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},
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ipsum: "primis"
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}
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};
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ReactDOM.render(<TreeView data={data} name='data'/>, document.getElementById("root"));
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```
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<!-- tags: object,visual,children,state,class -->
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<!-- expertise: 2 -->
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