反应钩子：输入 onChange 第一个字符不能删除

Question

I got some inputs to create/update a formular,

1) if value={question}, everything works except that I can not delete the last character (= first character of the input)

2) if I dont mention value, it's all good except when I want to change questions orders with Chevron icon button, database is well changed but input value is still displayed at the last place.

<input
        type="text"
        value={question}
        placeholder="blabla"
        onChange={event => {
          event.preventDefault();
         const value = event.target.value;
         setUpdatedQuestion(value);
        }}
      />

I tried to add if (event.target.value == "" || event.target.value) to onChange but does not work either

OK I found something, but it is a McGyver tip, not very clean : adding one space before all new add question ahah. But then I can't see my placeholder anymore :/

FYI : question is coming from a questions.map, setUpdatedQuestion do update questions, newOrder also do update questions

//in QuestionsContent.js (questions is a questions tab)
const QuestionsContent = props => {
return (
    <form onSubmit={onSubmit}>
      {isLoading === false && questions.length > 0
        ? questions.map((question, i) => {
            return (
              <div key={i}>
                <QuestionLine
                  {...question}
                  questions={questions}
                  setQuestions={setQuestions}
                  setNewOrder={setNewOrder}
                />
              </div>
            );
          })
        : null}

        <button 
          onClick={event => {
            event.preventDefault();
            setAddQuestion({
              question: null,
              type: "texte"
            });
          }}
        >
         Add a question
        </button>
</form>
);
};

//in QuestionLine.js:

const QuestionLine = ({
  question,
  setNewOrder,
  setQuestions,
  questions
}) => {
  const [updatedQuestion, setUpdatedQuestion] = useState("");

  // * UPDATE QUESTION *******************************
  useEffect(() => {
    if (updatedQuestion !== "") {
      const tab = [];

      for (let j = 0; j < questions.length; j++) {
        if (j === i) {
          const newObject = {
            question: updatedQuestion,
            type: type
          };
          console.log("adding updatedQuestion ===>", newObject);
          tab.push(newObject);
        } else {
          tab.push(questions[j]);
        }
      }
      setQuestions(tab);
      setUpdatedQuestion("");
    }
  }, [updatedQuestion]);

  return (
    <div >

      {/* QUESTION */}

      <input
        type="text"
        value={question}
        placeholder="blabla"
        onChange={event => {
          event.preventDefault();
         const value = event.target.value;
         setUpdatedQuestion(value);
        }}
      />   
    </div>
  );
};

thanks for your precious help

Answer 1

问题可能出在 useEffect 中的条件：当您要删除字符串的最后一个字符时，updatedQuestion 的状态为空，因此不执行条件