89 lines
7.9 KiB
Markdown
89 lines
7.9 KiB
Markdown
---
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id: 5a24c314108439a4d4036142
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title: Manage State Locally First
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challengeType: 6
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isRequired: false
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videoUrl: ''
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localeTitle: Administrar el estado localmente primero
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---
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## Description
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<section id="description"> Aquí terminarás de crear el componente <code>DisplayMessages</code> . </section>
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## Instructions
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<section id="instructions"> Primero, en el método <code>render()</code> , haga que el componente renderice un elemento de <code>input</code> , elemento de <code>button</code> y elemento <code>ul</code> . Cuando el elemento de <code>input</code> cambia, debe activar un método <code>handleChange()</code> . Además, el elemento de <code>input</code> debe representar el valor de la <code>input</code> que se encuentra en el estado del componente. El elemento de <code>button</code> debe activar un método <code>submitMessage()</code> cuando se hace clic. Segundo, escribe estos dos métodos. El método <code>handleChange()</code> debe actualizar la <code>input</code> con lo que el usuario está escribiendo. El método <code>submitMessage()</code> debe concatenar el mensaje actual (almacenado en la <code>input</code> ) a la matriz de <code>messages</code> en el estado local, y borrar el valor de la <code>input</code> . Finalmente, use la <code>ul</code> para mapear sobre la matriz de <code>messages</code> y procesarlos en la pantalla como una lista de elementos <code>li</code> . </section>
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## Tests
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<section id='tests'>
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```yml
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tests:
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- text: 'El componente <code>DisplayMessages</code> debe inicializarse con un estado igual a <code>{ input: "", messages: [] }</code> .'
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testString: 'assert((function() { const mockedComponent = Enzyme.mount(React.createElement(DisplayMessages)); const initialState = mockedComponent.state(); return ( typeof initialState === "object" && initialState.input === "" && initialState.messages.length === 0); })(), "The <code>DisplayMessages</code> component should initialize with a state equal to <code>{ input: "", messages: [] }</code>.");'
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- text: 'El componente <code>DisplayMessages</code> debe generar un <code>div</code> contenga un elemento <code>h2</code> , un elemento de <code>button</code> , un elemento <code>ul</code> y elementos <code>li</code> como elementos <code>li</code> .'
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(DisplayMessages)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); const state = () => { mockedComponent.setState({messages: ["__TEST__MESSAGE"]}); return waitForIt(() => mockedComponent )}; const updated = await state(); assert(updated.find("div").length === 1 && updated.find("h2").length === 1 && updated.find("button").length === 1 && updated.find("ul").length === 1, "The <code>DisplayMessages</code> component should render a <code>div</code> containing an <code>h2</code> element, a <code>button</code> element, a <code>ul</code> element, and <code>li</code> elements as children."); }; '
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- text: El elemento de <code>input</code> debe representar el valor de <code>input</code> en estado local.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(DisplayMessages)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); const causeChange = (c, v) => c.find("input").simulate("change", { target: { value: v }}); const testValue = "__TEST__EVENT__INPUT"; const changed = () => { causeChange(mockedComponent, testValue); return waitForIt(() => mockedComponent )}; const updated = await changed(); assert(updated.find("input").props().value === testValue, "The <code>input</code> element should render the value of <code>input</code> in local state."); }; '
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- text: Al llamar al método <code>handleChange</code> debe actualizar el valor de <code>input</code> en estado a la entrada actual.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(DisplayMessages)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); const causeChange = (c, v) => c.find("input").simulate("change", { target: { value: v }}); const initialState = mockedComponent.state(); const testMessage = "__TEST__EVENT__MESSAGE__"; const changed = () => { causeChange(mockedComponent, testMessage); return waitForIt(() => mockedComponent )}; const afterInput = await changed(); assert(initialState.input === "" && afterInput.state().input === "__TEST__EVENT__MESSAGE__", "Calling the method <code>handleChange</code> should update the <code>input</code> value in state to the current input."); }; '
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- text: Al hacer clic en el botón <code>Add message</code> se debe llamar al método <code>submitMessage</code> que debe agregar la <code>input</code> actual a la matriz de <code>messages</code> en el estado.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(DisplayMessages)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); const causeChange = (c, v) => c.find("input").simulate("change", { target: { value: v }}); const initialState = mockedComponent.state(); const testMessage_1 = "__FIRST__MESSAGE__"; const firstChange = () => { causeChange(mockedComponent, testMessage_1); return waitForIt(() => mockedComponent )}; const firstResult = await firstChange(); const firstSubmit = () => { mockedComponent.find("button").simulate("click"); return waitForIt(() => mockedComponent )}; const afterSubmit_1 = await firstSubmit(); const submitState_1 = afterSubmit_1.state(); const testMessage_2 = "__SECOND__MESSAGE__"; const secondChange = () => { causeChange(mockedComponent, testMessage_2); return waitForIt(() => mockedComponent )}; const secondResult = await secondChange(); const secondSubmit = () => { mockedComponent.find("button").simulate("click"); return waitForIt(() => mockedComponent )}; const afterSubmit_2 = await secondSubmit(); const submitState_2 = afterSubmit_2.state(); assert(initialState.messages.length === 0 && submitState_1.messages.length === 1 && submitState_2.messages.length === 2 && submitState_2.messages[1] === testMessage_2, "Clicking the <code>Add message</code> button should call the method <code>submitMessage</code> which should add the current <code>input</code> to the <code>messages</code> array in state."); }; '
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- text: El método <code>submitMessage</code> debería borrar la entrada actual.
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testString: 'async () => { const mockedComponent = Enzyme.mount(React.createElement(DisplayMessages)); const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 100)); const causeChange = (c, v) => c.find("input").simulate("change", { target: { value: v }}); const initialState = mockedComponent.state(); const testMessage = "__FIRST__MESSAGE__"; const firstChange = () => { causeChange(mockedComponent, testMessage); return waitForIt(() => mockedComponent )}; const firstResult = await firstChange(); const firstState = firstResult.state(); const firstSubmit = () => { mockedComponent.find("button").simulate("click"); return waitForIt(() => mockedComponent )}; const afterSubmit = await firstSubmit(); const submitState = afterSubmit.state(); assert(firstState.input === testMessage && submitState.input === "", "The <code>submitMessage</code> method should clear the current input."); }; '
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```
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</section>
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## Challenge Seed
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<section id='challengeSeed'>
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<div id='jsx-seed'>
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```jsx
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class DisplayMessages extends React.Component {
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constructor(props) {
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super(props);
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this.state = {
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input: ",
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messages: []
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}
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}
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// add handleChange() and submitMessage() methods here
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render() {
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return (
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<div>
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<h2>Type in a new Message:</h2>
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{ /* render an input, button, and ul here */ }
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{ /* change code above this line */ }
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</div>
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);
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}
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};
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```
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</div>
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### After Test
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<div id='jsx-teardown'>
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```js
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console.info('after the test');
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```
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</div>
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</section>
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## Solution
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<section id='solution'>
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```js
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// solution required
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```
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</section>
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