我已经建立了这个待办事项列表,几乎所有工作都很完美。但是,如果我删除列表中的所有内容。它不会让我添加一个新的条目,我似乎无法弄清楚为什么。只要列表中至少有一个条目,它就会正常工作。待办事项列表使用JavaScript/HTML
任何帮助非常感谢你。
<head>
< script type = "text/javascript" >
/*<![CDATA[*/
function addTask() {
if (document.forms[0].newtask.value == "")
window.alert("You must enter a value in the New Task field.");
else {
if (document.forms[0].tasks.options[0].value == "tasks")
document.forms[0].tasks.options[0] = null;
var newTask = new Option();
newTask.value = document.forms[0].newtask.value;
newTask.text = document.forms[0].newtask.value;
var numTasks = document.forms[0].tasks.options.length;
document.forms[0].tasks.options[numTasks] = newTask;
document.forms[0].newtask.value = "";
}
}
function deleteTask() {
var selectedTask = 0;
var taskSelected = false;
while (selectedTask < document.forms[0].tasks.length) {
if (document.forms[0].tasks.options[selectedTask].selected == true) {
taskSelected = true;
break;
}
++selectedTask;
}
if (taskSelected == true)
document.forms[0].tasks.options[selectedTask] = null;
else
window.alert("You must select a task in the list.");
}
function ascendingSort() {
var newTasks = new Array();
for (var i = 0; i < document.forms[0].tasks.length; ++i) {
newTasks[i] = document.forms[0].tasks.options[i].value;
}
newTasks.sort();
for (var j = 0; j < document.forms[0].tasks.length; ++j) {
document.forms[0].tasks.options[j].value = newTasks[j];
document.forms[0].tasks.options[j].text = newTasks[j];
}
}
/*]]>*/
< /script>
<title>To Do List</title >
< /head>
<body>
<h1>To Do List</h1>
<form action="">
<p>New Task
<input type="text" size="68" name="newtask" />
</p>
<p>
<input type="button" value="Add Task" onclick="addTask()" style="width: 150px" />
<input type="button" value="Delete Selected Task" onclick="deleteTask()" style="width: 150px" />
<br />
<input type="button" value="Ascending Sort" onclick="ascendingSort()" style="width: 150px" />
</p>
<p>
<select name="tasks" size="10" style="width: 500px">
<option value="tasks">Tasks</option>
</select>
</p>
</form>
</body>
Agh !!!我试过这个,但使用OR而不是AND。谢谢! – 2014-10-28 12:24:24