如何延迟表单提交

我正在为我的初级Javascript课程开发一个基本的Web表单。我几乎得到了我所有预期的结果(作业包括输入验证和按名称将元素存储在数组中(，除了当我提交表单时，我想从我点击提交到页面重定向时有 5 秒的延迟。此延迟是为了使用户能够取消订单。

从我们到目前为止在课堂上学到的知识来看，我希望我使用 setTimeout 代码块执行此操作 - 尽管我还无法做到这一点。我的表单提交依赖于被调用函数的真/假返回值，我想延迟该真值如此迅速地命中。我已经附加了我的完整 HTML 文件，但我想知道为什么它不起作用的代码块是这样的：

setTimeout(function() {
return true;
}, 5000);

我在 Chrome 中调试时观察到的第一个问题是，这不会将 True 值返回给周围的代码。

我认为可以用jQuery做一些事情来规避这一点，但我们还没有涵盖任何内容，所以我想避免走这条路。

```
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta name="description" content="Costello Improved">
<meta http-equiv="Content-type" content="text/html;charset=UTF-8" />
<title>Costellos Pasta and Pizza</title>
<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/4.0.0/css/bootstrap.min.css" integrity="sha384-Gn5384xqQ1aoWXA+058RXPxPg6fy4IWvTNh0E263XmFcJlSAwiGgFAW/dAiS6JXm" crossorigin="anonymous">
<link rel="stylesheet" href="costello.css">
</head>
<body>
<form name="myForm" action="https://costello-pasta.glitch.me/order" id="myForm" method="POST" onsubmit="return calculateOrder(this)">
<div class="container">
<div class="row">
<div class="col-md-12" id="debug">Costello's Online Orders</div>
</div>
<div class="row">
<div class="col-md-4  label">Pasta Bowl</div>
<div class="col-md-4"> (basic price: $7.50)</div>
<div class="col-md-4"></div>
</div>
<div class="row">
<div class="col-md-4  label">Pasta</div>
<div class="col-md-4">
<div><input type="radio" name="pastatype" value="0" />Spaghetti (no extra cost)</div>
<div><input type="radio" name="pastatype" value="50" />Fettucine (add 50 cents)</div>
<div><input type="radio" name="pastatype" value="75" />Fusilli (add 75 cents)</div>
</div>
<div class="col-md-4 msg" id="radioLabel"></div>
</div>
<div class="row">
<div class="col-md-4  label">Sauce</div>
<div class="col-md-4">
<select name="sauce">
<option value="0">Pomodoro (no extra cost)</option>
<option value="50">Bolognese (add 50 cents)</option>
<option value="100">Alfredo (add $1.00)</option>
</select>
</div>
<div class="col-md-4"></div>
</div>
<div class="row">
<div class="col-md-4  label">Extras</div>
<div class="col-md-4">
<div><input type="checkbox" name="extras" value="200" />Side salad (add $2.00)</div>
<div><input type="checkbox" name="extras" value="100" />Bread sticks (add $1.00)</div>
</div>
<div class="col-md-4"></div>
</div>
<div class="row">
<div class="col-md-4  label">Name</div>
<div class="col-md-4"><input type="text" id="name" name="client_name" /></div>
<div class="col-md-4 msg" id="nameLabel"></div>
</div>
<div class="row">
<div class="col-md-4  label">Phone</div>
<div class="col-md-4"><input type="text" id="phone" value="" /></div>
<div class="col-md-4 msg" id="phoneLabel"></div>
</div>
<div class="row">
<div class="col-md-4  label"><input type="submit" value="Order" /></div>
<div class="col-md-4" id="totalcost"></div>
<div class="col-md-4 msg" id="submitMessage"></div>
</div>
</div>
</form>
</body>
<script>
function calculateOrder() {
var totalCost = 750;
//Storing Pasta radio buttons into array.  Iterating through array and adding checked selection's value to the total cost. 
var submitBool = true;
var pastaArray = document.getElementsByName('pastatype');
for (var i = 0; i < pastaArray.length; i++) {
if (pastaArray[i].checked == true) {
totalCost = totalCost + parseInt(pastaArray[i].value);
}
//Validating Pasta input
}
if (pastaArray[0].checked == false && pastaArray[1].checked == false && pastaArray[2].checked == false) {
document.getElementById('radioLabel').innerHTML = "Required field! (You must choose a pasta)";
submitBool = false;
} else {
document.getElementById('radioLabel').innerHTML = "";
}
//Storing sauce selection into an array.  Adding price for selected option.
var sauceArray = document.getElementsByName('sauce');
totalCost = totalCost + parseInt(sauceArray[0].value);
//Storing extras selection(s) into an array.  Adding prices for selected options.   
var extraArray = document.getElementsByName('extras');
for (var x = 0; x < extraArray.length; x++) {
if (extraArray[x].checked == true) {
totalCost = totalCost + parseInt(extraArray[x].value);
}
}

//Validating Name input
if (document.getElementById('name').value == "") {
document.getElementById('nameLabel').innerHTML = "Required field!  Enter your name.";
submitBool = false;
} else {
document.getElementById('nameLabel').innerHTML = "";
}
//Validating Phone Number Input
var phone = document.getElementById('phone').value;
phone = phone.toString();
if (document.getElementById('phone').value == null) {
document.getElementById('phoneLabel').innerHTML = "Required field!  Enter your phone number.";
submitBool = false;
} else if (phone[3] != "-") {
document.getElementById('phoneLabel').innerHTML = "Enter in 888-888-8888 format!";
submitBool = false;
} else if (phone[7] != "-") {
document.getElementById('phoneLabel').innerHTML = "Enter in 888-888-8888 format!";
submitBool = false;
} else if (phone.length > 12 || phone.length < 12) {
document.getElementById('phoneLabel').innerHTML = "Enter in 888-888-8888 format!";
submitBool = false;
} else {
document.getElementById('phoneLabel').innerHTML = "";
}

//Form runs if input has been valid in all input options
if (submitBool == false) {
return false;
} else if (submitBool == true){
var preFixed = totalCost / 100;
var postFixed = preFixed.toFixed(2);

document.getElementById('totalcost').innerHTML = "Total Bill: $" + postFixed;
document.getElementById('submitMessage').innerHTML = "Order is being processed, <a>cancel?</a>"
setTimeout(function() {
return true;
}, 5000);
}
}
</script>
</html>
```

您可以使用onSubmit事件并延迟常规功能。我创建了一个简单的演示，因此您可以轻松理解它。提交表单后，它将在 5 秒后提交表单，或者如果您点击"取消"，则会被取消。

const myForm = document.getElementById('myForm');
myForm.addEventListener('submit', handleSubmit);
var submitTimer;
function handleSubmit(event) {
console.log('submitTimer set');
event.preventDefault();
submitTimer = setTimeout(() => {
this.submit();
console.log('Submitted after 5 seconds');
}, 5000)
};
function cancel(){
clearTimeout(submitTimer);
console.log('Submit Canceled');
}

<form id="myForm">
<input type="text" name="name"/>
<button type="submit">Submit</button>
<button type="button" onclick="cancel()" >Cancel</button>
</form>

setTimeout 函数在指定的毫秒数(在本例中为 5000(后调用函数或计算表达式。您在代码中所做的只是返回一个布尔值，而不创建通道来在时间流逝后获取值。由于此代码有点"异步"(需要时间(，因此可以使用内置的 Promise 函数来获取值。换句话说，你的代码可以重组成这样的东西：

getTheBoolValue = () => new Promise((resolve, reject) => {
setTimeout(function(){
resolve(true)
},5000)
})
getTheBoolValue().then(data => console.log(data))

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