Javascript ReactJS,更改存储在状态数组中的img src
首先,我要做的是:我有几个div,其中包含一些文本和一个图像。div的所有数据都存储在状态数组中。您还可以添加div和删除所需的任何div。我现在想实现的是,当用户单击图像时更改图片。有一个预设的图像库,每当用户单击图像时,应显示下一个图像 以下是一些相关代码:Javascript ReactJS,更改存储在状态数组中的img src,javascript,reactjs,Javascript,Reactjs,首先,我要做的是:我有几个div,其中包含一些文本和一个图像。div的所有数据都存储在状态数组中。您还可以添加div和删除所需的任何div。我现在想实现的是,当用户单击图像时更改图片。有一个预设的图像库,每当用户单击图像时,应显示下一个图像 以下是一些相关代码: let clicks = 0; class Parent extends React.Component { constructor(props) { super(props); this.sta
let clicks = 0;
class Parent extends React.Component {
constructor(props) {
super(props);
this.state = {
data : [
createData( someimage, "Image 1"),
createData( anotherimage, "Image 2"),
createData( thirdimage, "Image 3"),
createData( fourthimage, "Image 4"),
],
imgs : [imgsrc1,imgsrc2, imgsrc3, imgsrc4],
}
}
newIcon (n) {
let newStateArray = this.state.data.slice();
let newSubStateArray = newStateArray[n].slice();
if(clicks === 1) {
newSubStateArray[0] = this.state.imgs[0];
this.setState({imgsrc:newSubStateArray});
clicks++;
} else if (clicks === 2) {
newSubStateArray[0] = this.state.imgs[1];
this.setState({imgsrc:newSubStateArray});
clicks++;
} else if (clicks === 3) {
newSubStateArray[0] = this.state.imgs[2];
this.setState({imgsrc:newSubStateArray});
clicks++;
} else if (clicks === 4) {
newSubStateArray[0] = this.state.imgs[4];
this.setState({imgscr:newSubStateArray});
clicks++;
}
}
render () {
let { data }= this.state;
return(
<div>
{data.map((n) => {
return(
<Child imgsrc={n.imgsrc} key={n} newIcon={this.newIcon.bind(this, n)} header={n.header} />
);
})}
</div>
);
}
let clicks=0;
类父类扩展了React.Component{
建造师(道具){
超级(道具);
此.state={
数据:[
createData(someimage,“图像1”),
createData(另一个图像,“图像2”),
createData(第三页,“图像3”),
createData(第四幅图像,“图像4”),
],
imgs:[imgsrc1、imgsrc2、imgsrc3、imgsrc4],
}
}
新图标(n){
让newStateArray=this.state.data.slice();
让newSubStateArray=newStateArray[n].slice();
如果(单击===1){
newSubStateArray[0]=this.state.imgs[0];
this.setState({imgsrc:newSubStateArray});
点击++;
}否则如果(单击===2){
newSubStateArray[0]=this.state.imgs[1];
this.setState({imgsrc:newSubStateArray});
点击++;
}否则如果(单击===3){
newSubStateArray[0]=this.state.imgs[2];
this.setState({imgsrc:newSubStateArray});
点击++;
}否则如果(单击===4){
newSubStateArray[0]=this.state.imgs[4];
this.setState({imgscr:newSubStateArray});
点击++;
}
}
渲染(){
设{data}=this.state;
返回(
{data.map((n)=>{
返回(
);
})}
);
}
一些旁注:createArray是一个创建子数组的函数,对于这个问题可能可以忽略。需要知道的是,第一个元素称为imgsrc,第二个元素称为imgsrc
因此,这里出现了一些问题,但我不确定它到底是什么。我的猜测是,我没有正确地访问数组中的值。上面,您可以看到我尝试对数组进行切片,然后分配新值。我遇到的另一个问题是,当我尝试从我的newIcon()调用n时,n显示为未定义
-功能。
我有点迷路了,因为我是一个新手,所以欢迎任何类型的提示和建议。尝试在构造函数中绑定newIcon()方法,如下所示:
this.newIcon = this.newIcon.bind(this);
在render方法中,无需任何绑定即可正常调用:
this.newIcon(n)
我会删除
newIcon
中的所有代码,并将单击
作为状态的一部分。如果您有一个图像数组,则可以使用单击
作为指向下一个应显示图像的指针
在本例中,我随意添加了虚拟图像来帮助解释,并将单击
更改为指针
,因为这更有意义
class Parent extends React.Component {
constructor(props) {
super(props);
this.state = {
// clicks is called `pointer` here and initially
// is set to the first index of the imgs array
pointer: 0,
imgs: [
'https://dummyimage.com/100x100/000000/fff.png',
'https://dummyimage.com/100x100/41578a/fff.png',
'https://dummyimage.com/100x100/8a4242/fff.png',
'https://dummyimage.com/100x100/428a49/fff.png'
]
};
// Bind your class method in the constructor
this.handleClick = this.handleClick.bind(this);
}
// Here we get the length of the imgs array, and the current
// pointer position. If the pointer is at the end of the array
// set it back to zero, otherwise increase it by one.
handleClick() {
const { length } = this.state.imgs;
const { pointer } = this.state;
const newPointer = pointer === length - 1 ? 0 : pointer + 1;
this.setState({ pointer: newPointer });
}
render() {
const { pointer, imgs } = this.state;
// Have one image element to render. Every time the state is
// changed the src of the image will change too.
return (
<div>
<img src={imgs[pointer]} onClick={this.handleClick} />
</div>
);
}
}
类父级扩展React.Component{
建造师(道具){
超级(道具);
此.state={
//单击在此处和最初称为“指针”
//设置为imgs数组的第一个索引
指针:0,
imgs:[
'https://dummyimage.com/100x100/000000/fff.png',
'https://dummyimage.com/100x100/41578a/fff.png',
'https://dummyimage.com/100x100/8a4242/fff.png',
'https://dummyimage.com/100x100/428a49/fff.png'
]
};
//在构造函数中绑定类方法
this.handleClick=this.handleClick.bind(this);
}
//这里我们得到了imgs数组的长度和当前
//指针位置。如果指针位于数组的末尾
//将其设置回零,否则将其增加1。
handleClick(){
const{length}=this.state.imgs;
const{pointer}=this.state;
const newPointer=指针===长度-1?0:指针+1;
this.setState({pointer:newPointer});
}
render(){
const{pointer,imgs}=this.state;
//具有一个要渲染的图像元素。每次状态为
//更改图像的src也将更改。
返回(
);
}
}
编辑:因为您有多个div,其中的图像源需要更改,所以可能需要在父组件中保留一个图像数组,并将这些图像的子集作为道具传递给每个图像组件,然后存储在每个组件的状态中。这样,您就不需要对图像组件进行太多更改
class Image extends React.Component {
constructor(props) {
super(props);
this.state = { pointer: 0, imgs: props.imgs };
this.handleClick = this.handleClick.bind(this);
}
handleClick() {
const { length } = this.state.imgs;
const { pointer } = this.state;
const newPointer = pointer === length - 1 ? 0 : pointer + 1;
this.setState({ pointer: newPointer });
}
render() {
const { pointer, imgs } = this.state;
return (
<div>
<img src={imgs[pointer]} onClick={this.handleClick} />
</div>
);
}
}
class ImageSet extends React.Component {
constructor() {
super();
this.state = {
imgs: [
'https://dummyimage.com/100x100/000000/fff.png',
'https://dummyimage.com/100x100/41578a/fff.png',
'https://dummyimage.com/100x100/8a4242/fff.png',
'https://dummyimage.com/100x100/428a49/fff.png',
'https://dummyimage.com/100x100/bd86bd/fff.png',
'https://dummyimage.com/100x100/68b37c/fff.png',
'https://dummyimage.com/100x100/c9a7c8/000000.png',
'https://dummyimage.com/100x100/c7bfa7/000000.png'
]
}
}
render() {
const { imgs } = this.state;
return (
<div>
<Image imgs={imgs.slice(0, 4)} />
<Image imgs={imgs.slice(4, 8)} />
</div>
)
}
}
类映像扩展React.Component{
建造师(道具){
超级(道具);
this.state={指针:0,imgs:props.imgs};
this.handleClick=this.handleClick.bind(this);
}
handleClick(){
const{length}=this.state.imgs;
const{pointer}=this.state;
const newPointer=指针===长度-1?0:指针+1;
this.setState({pointer:newPointer});
}
render(){
const{pointer,imgs}=this.state;
返回(
);
}
}
类ImageSet扩展了React.Component{
构造函数(){
超级();
此.state={
imgs:[
'https://dummyimage.com/100x100/000000/fff.png',
'https://dummyimage.com/100x100/41578a/fff.png',
'https://dummyimage.com/100x100/8a4242/fff.png',
'https://dummyimage.com/100x100/428a49/fff.png',
'https://dummyimage.com/100x100/bd86bd/fff.png',
'https://dummyimage.com/100x100/68b37c/fff.png',
'https://dummyimage.com/100x100/c9a7c8/000000.png',
'https://dummyimage.com/100x100/c7bfa7/000000.png'
]
}
}
render(){
const{imgs}=this.state;
返回(
)
}