[英]JS event is firing when DOM is loaded
我正在設計一個有趣的測驗應用程序。 測驗將顯示一個問題,有四個選項可供回答。 我正在使用 vanilla JS 來更新 DOM,並且需要為呈現的每個答案添加一個 eventListener。 出於某種原因,一旦呈現 DOM, eventListener 就會觸發。 關於為什么的任何想法?
//add each answer to the answerContainer
answerContainer.innerHTML = '';
for (let i = 0; i < allAnswersFlattened.length; i++) {
let individualAnswer = document.createElement('div');
individualAnswer.className = 'answer';
let answerText = document.createTextNode(allAnswersFlattened[i]);
individualAnswer.appendChild(answerText);
individualAnswer.addEventListener("click", checkForAnswer(i, allAnswersFlattened));
answerContainer.appendChild(individualAnswer);
}
你需要這樣做:
individualAnswer.addEventListener("click", function() {
checkForAnswer(i, allAnswersFlattened));
});
但是隨后您會遇到i
不正確的問題(因為在單擊它時, i
值已增加。
所以可能你應該這樣做:
individualAnswer.addEventListener("click", ((i) => function() {
checkForAnswer(i, allAnswersFlattened));
})(i));
或者
individualAnswer.addEventListener("click", checkForAnswer.bind(this, i, allAnswersFlattened));
或者讓checkForAnswer
返回一個函數:
function checkForAnswer(i, allAnswers) => () => {
// whatever the code was before
}
您的事件正在觸發,因為您在此處調用該函數:
individualAnswer.addEventListener("click", checkForAnswer(i, allAnswersFlattened));
checkForAnswer(i, allAnswersFlattened) - 執行函數,而不是將其作為參數傳遞給 addEventListener
您需要做的是創建一個事件處理程序,您可以從中調用“checkForAnswer”(請參閱下面的 myEventListener):
answerContainer.innerHTML = '';
for (let i = 0; i < allAnswersFlattened.length; i++) {
var myEventListener = function(e) {
checkForAnswer(i, allAnswersFlattened)
};
let individualAnswer = document.createElement('div');
individualAnswer.className = 'answer';
let answerText = document.createTextNode(allAnswersFlattened[i]);
individualAnswer.appendChild(answerText);
individualAnswer.addEventListener("click", myEventListener );
answerContainer.appendChild(individualAnswer);
}
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