question number reordering
I have a list of question in my javascript file. Each question has a question number and question description and options. A question can be added anywhere in the list of questions. So if a question is added into the top of all questions, then i need to change the开发者_JS百科 question numbers of all the below ones. How can achieve this. Can i use javascript for this?
I would suggest using an <ol> for each question, and let the page handle reflowing the numbers.
Otherwise you'll need to set a target number before inserting, and for each element in the list you'll check to see if it's number is greater than the target, and then if so increment the number by one.
var Target = //new number that I want the inserted question to be
foreach (element in list) {
if (element.Number > Target) element.Number += 1;
}
list.add( //new question with # set to Target );
This works.
<ol id="questions_list"></ol>
var questions = ["A foo walks into a bar. What happens?", "Why did foo cross the road?"];
addQuestion("foo", 1);
function addQuestion(question, position)
{
if(position > 0 && position < questions.length)
{
var firstHalf = questions.slice(0, position);
var secondHalf = questions.slice(position, questions.length);
firstHalf.push(question);
questions = firstHalf.concat(secondHalf);
console.log("slice");
}else if(position <= 0)
{
questions.unshift(question);
console.log("beginning");
}else if(position >= questions.length)
{
questions.push(question);
console.log("end");
}
updateQuestionList();
}
function updateQuestionList()
{
var questions_list = document.getElementById("questions_list");
questions_list.innerHTML = "";
for(var i=0;i<questions.length;i++)
{
var question = document.createElement("LI");
question.innerHTML = questions[i];
questions_list.appendChild(question);
}
}
http://jsfiddle.net/jPxwW/1/
Array prototype ( fun! =) ):
// zero-based insert
Array.prototype.insert = function(index, item) {
var i = 0, list = [];
if (this.length == index) {
list = this;
list.push(item);
return list;
}
for(; i < this.length; i++) {
if (index == list.length) {
list.push(item);
i--;
} else {
list.push(this[i]);
}
}
return list;
};
Array.prototype.print = function (base) {
base = base || 1;
for (var i = 0, out = []; i < this.length; i++) {
out.push((base + i) + '. ' + this[i]);
}
return out.join("\n");
};
list = ['when?', 'where?', 'why?'];
list = list.insert(0, 'who?'); // first: ["who?", "when?", "where?", "why?"]
list = list.insert(3, 'how?'); // 4th: ["who?", "when?", "where?", "how?", "why?"]
list = list.insert(list.length, 'last?'); // last: ["who?", "when?", "where?", "how?", "why?", "last?"];
list.print();
/**
"1. who?
2. when?
3. where?
4. how?
5. why?
6. last?"
**/
You could do something like this using ordered lists (ol) and jQuery:
<html>
<head>
<script src="http://code.jquery.com/jquery-1.4.4.min.js" type="text/javascript"></script>
<script type ="text/javascript">
$(function(){
var n = 2;
$('button').delegate('click', function(){
$(this).parents('li').after('<li><p><span>Question'+n+'</span><button>Create new question</button></p></li>');
n += 1;
})
})
</script>
</head>
<body>
<ol>
<li>
<p><span>Question 1</span><button>Create new question</button></p>
</li>
</ol>
</body>
</html>
加载中,请稍侯......
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