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Reactjs {payment.fname} )) } 您实际上是在设置状态,这会导致重新启动,设置状态,重新启动,等等。这在功能上是不等价的,它在以后每次打开菜单时都显示--选择一个状态--,而最初的实现只在最初显示它。@AvinKavish,我不明白您的意思。在Ry_Reactjs_React Hooks - Fatal编程技术网

Reactjs {payment.fname} )) } 您实际上是在设置状态,这会导致重新启动,设置状态,重新启动,等等。这在功能上是不等价的,它在以后每次打开菜单时都显示--选择一个状态--,而最初的实现只在最初显示它。@AvinKavish,我不明白您的意思。在Ry

Reactjs {payment.fname} )) } 您实际上是在设置状态,这会导致重新启动,设置状态,重新启动,等等。这在功能上是不等价的,它在以后每次打开菜单时都显示--选择一个状态--,而最初的实现只在最初显示它。@AvinKavish,我不明白您的意思。在Ry,reactjs,react-hooks,Reactjs,React Hooks,{payment.fname} )) } 您实际上是在设置状态,这会导致重新启动,设置状态,重新启动,等等。这在功能上是不等价的,它在以后每次打开菜单时都显示--选择一个状态--,而最初的实现只在最初显示它。@AvinKavish,我不明白您的意思。在Ryan的演示中,“---选择一个状态---”根本不显示,可以省略。你能解释一下你的意思吗?哦,是的,我只是假设,因为它被称为初始值,它的行为应该是这样的。我的回答显示了一个实现,其中“选择状态”最初显示,但消失,无法重新拾取。@AvinKavis

{payment.fname} )) }
您实际上是在设置状态,这会导致重新启动,设置状态,重新启动,等等。这在功能上是不等价的,它在以后每次打开菜单时都显示
--选择一个状态--
,而最初的实现只在最初显示它。@AvinKavish,我不明白您的意思。在Ryan的演示中,“---选择一个状态---”根本不显示,可以省略。你能解释一下你的意思吗?哦,是的,我只是假设,因为它被称为初始值,它的行为应该是这样的。我的回答显示了一个实现,其中“选择状态”最初显示,但消失,无法重新拾取。@AvinKavish,酷。顺便说一句,我的新工作似乎已经通知你了。怎么会这样?我也想使用这个解决方案。
    import React, { useState } from "react"; 
    import ReactDOM from "react-dom";

    const StateSelector = () => {   
    const initialValue = [
    { id: 0,value: " --- Select a State ---" }];

      const allowedState = [
        { id: 1, value: "Alabama" },
        { id: 2, value: "Georgia" },
        { id: 3, value: "Tennessee" }
        ];

      const [stateOptions, setStateValues] = useState(initialValue);  
      // initialValue.push(...allowedState);

      console.log(initialValue.length);

      setStateValues(allowedState); // Not sure why cannot I reset the state in here for an array.

         return (<div>
          <label>Select a State:</label>
          <select>
            {stateOptions.map((localState, index) => (
              <option key={localState.id}>{localState.value}</option>
            ))}
          </select>
        </div>   ); };

    const rootElement = document.getElementById("root");
    ReactDOM.render(<StateSelector />, rootElement);
import React, { useState, useEffect } from "react";
import ReactDOM from "react-dom";

const StateSelector = () => {
  const initialValue = [
    { id: 0, value: " --- Select a State ---" }];

  const allowedState = [
    { id: 1, value: "Alabama" },
    { id: 2, value: "Georgia" },
    { id: 3, value: "Tennessee" }
  ];

  const [stateOptions, setStateValues] = useState(initialValue);
  // initialValue.push(...allowedState);

  console.log(initialValue.length);
  // ****** BEGINNING OF CHANGE ******
  useEffect(() => {
    // Should not ever set state during rendering, so do this in useEffect instead.
    setStateValues(allowedState);
  }, []);
  // ****** END OF CHANGE ******

  return (<div>
    <label>Select a State:</label>
    <select>
      {stateOptions.map((localState, index) => (
        <option key={localState.id}>{localState.value}</option>
      ))}
    </select>
  </div>);
};

const rootElement = document.getElementById("root");
ReactDOM.render(<StateSelector />, rootElement);
const StateSelector = () =>{
  const [selectedStateOption, setselectedStateOption] = useState(0);

  return (
    <div>
      <label>Select a State:</label>
      <select>
        {ALL_STATE_VALS.map((option, index) => (
          <option key={option.id} selected={index===selectedStateOption}>{option.value}</option>
        ))}
      </select>
    </div>);
   )
}
import React, { useState } from "react"; 
import ReactDOM from "react-dom";

const initialValue = { id: 0,value: " --- Select a State ---" };

const options = [
    { id: 1, value: "Alabama" },
    { id: 2, value: "Georgia" },
    { id: 3, value: "Tennessee" }
];

const StateSelector = () => {   
   const [ selected, setSelected ] = useState(initialValue);  

     return (
       <div>
          <label>Select a State:</label>
          <select value={selected}>
            {selected === initialValue && 
                <option disabled value={initialValue}>{initialValue.value}</option>}
            {options.map((localState, index) => (
               <option key={localState.id} value={localState}>
                   {localState.value}
               </option>
             ))}
          </select>
        </div>
      ); 
};

const rootElement = document.getElementById("root");
ReactDOM.render(<StateSelector />, rootElement);
setStateValues(allowedState);
  setTimeout(
    () => setStateValues(allowedState),
    1000
  )
let paymentList = [
    {"id":249,"txnid":"2","fname":"Rigoberto"}, {"id":249,"txnid":"33","fname":"manuel"},]
<div className="card-body">
            <div className="table-responsive">
                <table className="table table-striped">
                    <thead>
                        <tr>
                            <th>Transaction ID</th>
                            <th>Name</th>
                        </tr>
                    </thead>
                    <tbody>
                        {
                            paymentList.map((payment, key) => (
                                <tr key={key}>
                                    <td>{payment.txnid}</td>
                                    <td>{payment.fname}</td>
                                </tr>
                            ))
                        }
                    </tbody>
                </table>
            </div>
        </div>