input
和textarea
等某些元素的内部状态,这使得它们成为受控组件。这也适用于其他表单元素,包括常规HTML form
元素。 MyForm
组件设置为带有提交处理程序的空form
。提交表单时将调用提交处理程序。我们添加了一个提交表单的按钮。您可以看到它的type
设置为submit
表明它是控制表单的按钮。在form
添加input
元素并设置其value
和onChange()
属性, onChange()
一个挑战。然后,您应该完成handleSubmit
方法,以便将组件状态属性submit
设置为本地state
的当前输入值。 注意:您还必须在提交处理程序中调用event.preventDefault()
,以防止将刷新网页的默认表单提交行为。最后,在form
之后创建一个h1
标记,该form
从组件的state
呈现submit
值。然后,您可以键入表单并单击按钮(或按Enter键),您应该看到您的输入呈现给页面。 MyForm
应该返回一个包含form
和h1
标记的div
元素。表单应包含input
和button
。
testString: 'assert((() => { const mockedComponent = Enzyme.mount(React.createElement(MyForm)); return (mockedComponent.find("div").children().find("form").length === 1 && mockedComponent.find("div").children().find("h1").length === 1 && mockedComponent.find("form").children().find("input").length === 1 && mockedComponent.find("form").children().find("button").length === 1) })(), "MyForm
should return a div
element which contains a form
and an h1
tag. The form should include an input
and a button
.");'
- text: MyForm
的状态应该使用input
和submit
属性初始化,两者都设置为空字符串。
testString: 'assert(Enzyme.mount(React.createElement(MyForm)).state("input") === "" && Enzyme.mount(React.createElement(MyForm)).state("submit") === "", "The state of MyForm
should initialize with input
and submit
properties, both set to empty strings.");'
- text: 输入input
元素应该更新组件状态的input
属性。
testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyForm)); const _1 = () => { mockedComponent.setState({ input: "" }); return waitForIt(() => mockedComponent.state("input"))}; const _2 = () => { mockedComponent.find("input").simulate("change", { target: { value: "TestInput" }}); return waitForIt(() => ({ state: mockedComponent.state("input"), inputVal: mockedComponent.find("input").props().value }))}; const before = await _1(); const after = await _2(); assert(before === "" && after.state === "TestInput" && after.inputVal === "TestInput", "Typing in the input
element should update the input
property of the component's state."); }; '
- text: 提交表单应该运行handleSubmit
,它应该将submit
属性设置为等于当前输入的状态。
testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyForm)); const _1 = () => { mockedComponent.setState({ input: "" }); mockedComponent.setState({submit: ""}); mockedComponent.find("input").simulate("change", {target: {value: "SubmitInput"}}); return waitForIt(() => mockedComponent.state("submit"))}; const _2 = () => { mockedComponent.find("form").simulate("submit"); return waitForIt(() => mockedComponent.state("submit"))}; const before = await _1(); const after = await _2(); assert(before === "" && after === "SubmitInput", "Submitting the form should run handleSubmit
which should set the submit
property in state equal to the current input."); };'
- text: h1
标头应该从组件的状态呈现submit
字段的值。
testString: 'async () => { const waitForIt = (fn) => new Promise((resolve, reject) => setTimeout(() => resolve(fn()), 250)); const mockedComponent = Enzyme.mount(React.createElement(MyForm)); const _1 = () => { mockedComponent.setState({ input: "" }); mockedComponent.setState({submit: ""}); mockedComponent.find("input").simulate("change", {target: {value: "TestInput"}}); return waitForIt(() => mockedComponent.find("h1").text())}; const _2 = () => { mockedComponent.find("form").simulate("submit"); return waitForIt(() => mockedComponent.find("h1").text())}; const before = await _1(); const after = await _2(); assert(before === "" && after === "TestInput", "The h1
header should render the value of the submit
field from the component's state."); }; '
```