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[英]How to fix "undefined" array when reading a file into an array with readFile
[英]How to fix undefined array
我对 javascript 相当陌生,因此感谢您提供任何帮助。 我正在尝试从用户收集 2 个相关输入并将数组对象显示为表格。 但是,当提交输入时,数组显示为未定义。 我不确定我哪里出错了。 有什么建议?
我尝试了不同的方法来从表单中收集输入,但似乎都没有奏效。
<!DOCTYPE html>
<html>
<head>
<meta charset="ISO-8859-1">
<title>Example:</title>
<script type="text/javascript">
var flights = [];
function add(ele) {
flights.push(number, miles);
render();
document.getElementById("number").value = "";
document.getElementById("miles").value = "";
}
function render() {
document.getElementById("mydiv").innerHTML = "";
thelisthtml = "";
for(i = 0; i< flights.length; i++)
thelisthtml += "<div class='card' id="+ i +"><div class='card-body'>";
thelisthtml += "Flight " + (i+1) + " : " + flights[i] + " " + "<button type='submit' onclick = 'clearToDo(this)' id="+ i +">Remove From List</button>";
document.getElementById("mydiv").innerHTML = thelisthtml;
}
function calculateStatus(){
var totalMiles = Number(document.getElementById("totalMiles").value);
if (miles < 9999){
tr = document.getElementById("table").rows[1];
tr.style.backgroundColor = "yellow";
}
if (miles >= 10000 && miles <= 24999){
tr = document.getElementById("table").rows[2];
tr.style.backgroundColor = "yellow";
}
if (miles >= 25000){
tr = document.getElementById("table").rows[3];
tr.style.backgroundColor = "yellow";
}
}
function refreshPage() {
window.location.reload();
}
</script>
</head>
<body>
<br>
<table id="table" border ="1">
<tr>
<th>Medallion Status</th>
<th>Level</th>
</tr>
<tr>
<td>Bronze</td>
<td> < 10000 miles</td>
</tr>
<tr>
<td>Silver</td>
<td> < 25000 miles</td>
</tr>
<tr>
<td>Gold</td>
<td> > 25000</td>
</tr>
</table>
<h1><strong>Traveler Information </strong></h1><br> <br>
Flight Number: <input type="text" id="number" name="number" value="" />
<br> <br>
Miles Flown: <input type="text" id="miles" name="miles" value=""/> <br>
<br>
<input type="submit" value="Add Flight" id="go" onclick="add(this)"/>
<p>----------------------------</p>
<table>
<thead>
<tr>
<th>Flight</th>
<th>Miles</th>
</tr>
<thead>
<tbody>
<tr class="col-md-6" id="mydiv"></tr>
</tbody>
</table>
<input type="reset" id="reset" name="Reset" value="Reset"
onclick="refreshPage()" /> <br> <br> <br>
<br> <br>
</body>
</html>
预期的结果是数组将在用户输入信息时显示在表格中。 实际结果是数组未定义。
有几个问题,但关于如何修复包含undefined
的flights
数组的问题的答案是更改
function add(ele) {
flights.push(number, miles);
render();
document.getElementById("number").value = "";
document.getElementById("miles").value = "";
}
到
function add() {
const numberElem = document.getElementById("number");
const milesElem = document.getElementById("miles");
flights.push(numberElem.value, milesElem.value);
render();
numberElem.value = "";
milesElem.value = "";
}
在您的原始add
函数中,您将number
和miles
number
推送到flights
数组上,但number
和miles
number
是未定义的变量,因此您将undefined
和undefined
推送到flights
数组上。
为了解决其他问题,我建议用以下内容替换您的add
和render
功能
function add() {
const numberElem = document.getElementById("number");
const milesElem = document.getElementById("miles");
flights.push({
number: numberElem.value,
miles: milesElem.value});
render();
numberElem.value = "";
milesElem.value = "";
}
function render() {
const tbody = document.querySelector('#outputTable tbody');
tbody.innerHTML = flights.map((flight, i) => {
return ''
+ '<tr>'
+ '<td>'
+ flight.number
+ '</td>'
+ '<td>'
+ flight.miles
+ '</td>'
+ '<td>'
+ `<button type='button' onclick="clearToDo(${i})">`
+ 'Remove From List'
+ '</button>'
+ '</td>'
+ '</tr>';
}).join('');
}
并将您的第二个<table>
更改为<table id="outputTable">
。
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