Reactjs 我正在学习react,我的代码运行良好,但如何一次性声明currDate以在useState中全局使用它
如何全局声明currDate以在useState中使用它。下面的代码工作得很好,但希望提高效率 有没有更好的方法来缩短代码Reactjs 我正在学习react,我的代码运行良好,但如何一次性声明currDate以在useState中全局使用它,reactjs,mern,reactjs-flux,react-fullstack,reactjs-testutils,Reactjs,Mern,Reactjs Flux,React Fullstack,Reactjs Testutils,如何全局声明currDate以在useState中使用它。下面的代码工作得很好,但希望提高效率 有没有更好的方法来缩短代码 import React, { useState } from "react"; const Clock = () => { const date = new Date(); const currDate = date.toLocaleTimeString(); const [currTime, updateTime]
import React, { useState } from "react";
const Clock = () => {
const date = new Date();
const currDate = date.toLocaleTimeString();
const [currTime, updateTime] = useState(currDate);
console.log(currDate);
const timeHandler = () => {
console.log(1);
const date = new Date();
const currDate = date.toLocaleTimeString();
updateTime(currDate);
};
return (
<>
<h1> {currTime}</h1>
<button type="button" onClick={timeHandler}>
Updatetime
</button>
</>
);
};
export default Clock;
import React,{useState}来自“React”;
常数时钟=()=>{
const date=新日期();
const currDate=date.toLocaleTimeString();
const[currTime,updateTime]=useState(currDate);
console.log(当前日期);
常量时间处理程序=()=>{
控制台日志(1);
const date=新日期();
const currDate=date.toLocaleTimeString();
更新时间(当前日期);
};
返回(
{currTime}
更新时间
);
};
输出默认时钟;
如果您希望使其简短,而不是重复从到LocaleTimeString
获取的currDate
行。您可以创建一个这样做的函数,并在任何需要的地方使用它
示例-1
如果您希望使其简短,而不是重复从
toLocaleTimeString
获取currDate
的行。您可以创建一个这样做的函数,并在任何需要的地方使用它
示例-1
像这样的东西对你有用吗
1 import React, { useState } from 'react';
2
3 const getTime = () => {
4 const date = new Date();
5 const currDate = date.toLocaleTimeString();
6
7 return currDate;
8 };
9
10 function Clock() {
11 const [currTime, updateTime] = useState(getTime());
12
13 const timeHandler = () => {
14 updateTime(getTime());
15 };
16
17 return (
18 <>
19 <h1> {currTime}</h1>
20 <button type="button" onClick={timeHandler}>
21 Updatetime
22 </button>
23 </>
24 );
25 }
26
27 export default Clock;
1导入React,{useState}来自'React';
2.
3常量getTime=()=>{
4 const date=新日期();
5 const currDate=date.toLocaleTimeString();
6.
7返回日期;
8 };
9
10功能时钟(){
11 const[currTime,updateTime]=useState(getTime());
12
13常量时间处理程序=()=>{
14 updateTime(getTime());
15 };
16
17返回(
18
19{currTime}
20
21更新时间
22
23
24 );
25 }
26
27输出默认时钟;
像这样的东西对你有用吗
1 import React, { useState } from 'react';
2
3 const getTime = () => {
4 const date = new Date();
5 const currDate = date.toLocaleTimeString();
6
7 return currDate;
8 };
9
10 function Clock() {
11 const [currTime, updateTime] = useState(getTime());
12
13 const timeHandler = () => {
14 updateTime(getTime());
15 };
16
17 return (
18 <>
19 <h1> {currTime}</h1>
20 <button type="button" onClick={timeHandler}>
21 Updatetime
22 </button>
23 </>
24 );
25 }
26
27 export default Clock;
1导入React,{useState}来自'React';
2.
3常量getTime=()=>{
4 const date=新日期();
5 const currDate=date.toLocaleTimeString();
6.
7返回日期;
8 };
9
10功能时钟(){
11 const[currTime,updateTime]=useState(getTime());
12
13常量时间处理程序=()=>{
14 updateTime(getTime());
15 };
16
17返回(
18
19{currTime}
20
21更新时间
22
23
24 );
25 }
26
27输出默认时钟;
1 import React, { useState } from 'react';
2
3 const getTime = () => {
4 const date = new Date();
5 const currDate = date.toLocaleTimeString();
6
7 return currDate;
8 };
9
10 function Clock() {
11 const [currTime, updateTime] = useState(getTime());
12
13 const timeHandler = () => {
14 updateTime(getTime());
15 };
16
17 return (
18 <>
19 <h1> {currTime}</h1>
20 <button type="button" onClick={timeHandler}>
21 Updatetime
22 </button>
23 </>
24 );
25 }
26
27 export default Clock;