这是代码如何禁用提交按钮。它似乎对我们不起作用。我希望能够在打开页面时禁用该按钮。您对我们如何解决此问题有任何想法吗?
// Script 10.5 - pizza.js
// This script creates a master checkbox.
// Function called when the checkbox's value changes.
// Function toggles all the other checkboxes.
function toggleCheckboxes() {
'use strict';
// Get the master checkbox's value:
var status = document.getElementById('toggle').checked;
// Get all the checkboxes:
var boxes = document.querySelectorAll('input[type="checkbox"]');
// Loop through the checkboxes, starting with the second:
for (var i = 1, count = boxes.length; i < count; i++) {
// Update the checked property:
boxes[i].checked = status;
} // End of FOR loop.
}
} // End of toggleCheckboxes() function.
function disabled () {
if ('')
{document.getElementById('submit').disabled = false;}
else
{document.getElementById('submit').disabled = true;}
// Establish functionality on window load:
window.onload = function() {
'use strict';
// Add an event handler to the master checkbox:
document.getElementById('toggle').onchange = toggleCheckboxes;
document.getElementById('submit').disabled = disabled;
};
这是html
<!doctype html>
<html lang="en">
<head>
<meta charset="utf-8">
<title>Operating Systems</title>
<!--[if lt IE 9]>
<script </script>
<![endif]-->
</head>
<body>
<!-- Script 10.4 - pizza.html -->
<form action="#" method="post" id="theForm">
<fieldset><legend>Create Your Own Pizza</legend>
<div><label>Toppings</label> <input type="checkbox" name="toggle" id="toggle" value="toggle"> All/None
<p><input type="checkbox" name="ham" id="ham" value="ham"> Ham
<input type="checkbox" name="mushrooms" id="mushrooms" value="mushrooms"> Mushrooms
<input type="checkbox" name="onions" id="onions" value="onions"> Onions
<input type="checkbox" name="sausage" id="sausage" value="sausage"> Sausage
<input type="checkbox" name="greenPeppers" id="greenPeppers" value="greenPeppers"> Green Peppers </p>
</div>
<input type="checkbox" name="terms" id="terms" required> I agree to the terms, whatever they are.
<input type="submit" name="submit" value="Submit" id="submit">
</fieldset>
<div id="output"></div>
</form>
<script src="js/utilities.js"></script>
<script src="js/pizza.js"></script>
<script src="js/modal.js"></script>
</body>
</html>