我正在学习反应并且我的代码工作正常但我如何声明 currDate 一次以全局使用它以在 useState 中使用
I am learning react and my code is working fine but how can i declare currDate single time to use it globally to use in useState
如何全局声明 currDate 以在 useState 中使用它。以下代码工作正常,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] = 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;
如果您想缩短它,而不是重复从 toLocaleTimeString
获取 currDate
的行。您创建一个函数来执行此操作,并在任何需要的地方使用它。
示例 - 1
function getCurrDate() {
return (new Date()).toLocaleTimeString()
}
const Clock = () => {
const [currTime, updateTime] = useState(getCurrDate());
return (
<>
<h1> {currTime}</h1>
<button type="button" onClick={() => updateTime(getCurrDate())}>
Updatetime
</button>
</>
);
};
export default Clock;
示例 - 2
将最近的日期存储在状态中并从中导出 toLocaleTimeString()
。
const Clock = () => {
const [currTime, updateTime] = useState(new Date());
return (
<>
<h1> {currTime.toLocaleTimeString()}</h1>
<button type="button" onClick={() => updateTime(new Date())}>
Updatetime
</button>
</>
);
};
export default Clock;
这样的事情对你有用吗?
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;
如何全局声明 currDate 以在 useState 中使用它。以下代码工作正常,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] = 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;
如果您想缩短它,而不是重复从 toLocaleTimeString
获取 currDate
的行。您创建一个函数来执行此操作,并在任何需要的地方使用它。
示例 - 1
function getCurrDate() {
return (new Date()).toLocaleTimeString()
}
const Clock = () => {
const [currTime, updateTime] = useState(getCurrDate());
return (
<>
<h1> {currTime}</h1>
<button type="button" onClick={() => updateTime(getCurrDate())}>
Updatetime
</button>
</>
);
};
export default Clock;
示例 - 2
将最近的日期存储在状态中并从中导出 toLocaleTimeString()
。
const Clock = () => {
const [currTime, updateTime] = useState(new Date());
return (
<>
<h1> {currTime.toLocaleTimeString()}</h1>
<button type="button" onClick={() => updateTime(new Date())}>
Updatetime
</button>
</>
);
};
export default Clock;
这样的事情对你有用吗?
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;