[英]Add prop when onClick in ReactJS
單擊后,我想更改當前li項目的顏色。
當我單擊道具時如何向道具添加道具(使用數組映射)? 我使用樣式組件
const Li = styled.li`
color: ${props => (props.checked ? "red" : "green")};
`;
class App extends Component {
constructor(props) {
super(props);
this.state = {
value: "",
items: []
};
}
render() {
const ShowItems = this.state.items.map((item, index) => {
return (
<Li key={index}>
{item}
<button onClick={() => this.deleteItemHandler(index)}> Delete</button>
</Li>
);
});
return (
<Wrapper>
<AddItem
addItemHandler={this.addItem}
InputValue={this.state.value}
InputValueHandler={this.inputValue}
/>
{ShowItems}
</Wrapper>
);
}
}
因此,您需要跟蹤活動索引,並使用它來更改活動組件顏色的顏色。
state ={
activeIndex: void 0
}
const Li = styled.li`
color: ${props => props.checked ? "red" : "green"};
;`
deleteItemHandler = (index) => {
this.setState({
activeIndex: index
})
}
render() {
const ShowItems = this.state.items.map((item, index) => {
return (
<Li key={index} checked={index === this.state.activeIndex} > {item} < button onClick={() => this.deleteItemHandler(index)
}> Delete</button ></Li >
)
})
return (
<Wrapper>
<AddItem
addItemHandler={this.addItem}
InputValue={this.state.value}
InputValueHandler={this.inputValue}
/>
{ShowItems}
</Wrapper>
);
嘗試這個
const Li = styled.li`
color: ${props => props.checked ? "red" : "green"};
;`
class App extends Component {
constructor(props) {
super(props);
this.state = {
value: "",
items: [],
currentChecked: null
};
}
render() {
const ShowItems = this.state.items.map((item, index) => {
return (
<Li key={index} checked={index === this.state.currentChecked} >
{item}
<button onClick={() => this.setState({currentChecked: index})}>Delete</button >
</Li >
)
})
return (
<Wrapper>
<AddItem
addItemHandler={this.addItem}
InputValue={this.state.value}
InputValueHandler={this.inputValue}
/>
{ShowItems}
</Wrapper>
);
看看在CodeSandBox上工作的這段代碼
import React, { Component } from "react";
import ReactDOM from "react-dom";
import "./styles.css";
import styled from "styled-components";
const Li = styled.li`
color: ${props => (props.checked ? "red" : "green")};
`;
class App extends Component {
state = {
value: "",
items: [],
selected: -1
};
handleChange = e => {
this.setState({
[e.currentTarget.name]: e.currentTarget.value
});
};
handleAdd = () => {
const { items, value } = this.state;
this.setState({
items: [...items, value],
value: ""
});
};
handleRemove = index => {
const { items, selected } = this.state;
items.splice(index, 1);
if (index < selected) index = selected - 1;
if (index === selected) index = -1;
if (index > selected) index = selected;
this.setState({
items: items,
selected: index
});
};
handleActiveItem = index => {
this.setState({ selected: index });
};
render() {
const { value, items, selected } = this.state;
return (
<div>
<input
type="text"
value={value}
name="value"
onChange={this.handleChange}
/>
<button
style={{ margin: "0px 5px" }}
disabled={!value}
className="btn btn-sm btn-success"
onClick={this.handleAdd}
>
+
</button>
<ul className="li">
{items.map((item, index) => (
<Li key={index} checked={selected === index}>
<span onClick={() => this.handleActiveItem(index)}>{item}</span>
<button
style={{ margin: "1px 5px" }}
className="btn btn-sm btn-danger"
onClick={() => this.handleRemove(index)}
>
X
</button>
</Li>
))}
</ul>
</div>
);
}
}
const rootElement = document.getElementById("root");
ReactDOM.render(<App />, rootElement);
如果不需要處理程序,請忽略它們。 由於這項工作,我了解了styled-components
並發現了CodeSandBox。
編輯:
<span> inside <li>
添加了<span> inside <li>
以避免嵌套onClick
,以前的<li>
(父級)和<button>
(子級)都具有onClick
屬性。 “單擊按鈕”觸發了兩個onClick事件,在某些用例中導致意外行為。 您必須在代碼中更正此錯誤 。
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