Develop Reference

How can I access variable from a concatenated script that holds another script inside it?

I have this code to open a file in NW.JS.
function chooseFile(name, handleFile) {
var chooser = document.querySelector(name);
chooser.addEventListener("change", function(evt) {
for(var f of this.files){
console.log(f.name);
console.log(f.path);
handleFile(f.name, f.path);
}
}, false);
chooser.click();
}
chooseFile('#fileDialog', function(name, path){ ... /* do something with the file(s) */ });
I have concatenated that code into a string so that I can inject it into a div (when that div is created) from a button click that generates the above code with unique id’s thusly..
var letsDoThis = '$(".' + imgUploadClass + '").click(function(){ var leid = this.id; var theEditId = "divId" + leid.slice(5); function ' + imgUploadChoose + '(name, handleFile) { var chooser = document.querySelector(name);chooser.addEventListener("change", function(evt) { for(var f of this.files){console.log(f.name);console.log(f.path);handleFile(f.name, f.path);}}, false);chooser.click();}' + imgUploadChoose + '("#' + imgUploadzz +'", function(name, path){' + 'alert(path);' + ';});});';
When testing I can access the name and path inside the alert box! GREAT! The code I want to run where
'alert("Hello!");’
is needs to be the following (but instead of a hardcoded url I need to access “path” from the (uniquely named) chooseFile script)...
'$("#" +' + 'theEditId).css("background-image", "url(http://www.jqueryscript.net/images/Simplest-Responsive-jQuery-Image-Lightbox-Plugin-simple-lightbox.jpg)");'
I am pretty sure I am not escaping a comma or something, here is another piece of code I got to fire correctly but not being able to access “path”...
'$("#" +' + 'theEditId).css("background-color", "green");'

Making use of a JSON attribute that doesn't always exist. Using jquery

I am writing a short script that connects to the LastFM api to get my last scrobbled song. The issue I am having is that the JSON version has an attribute for "now playing" which when you are currently listening to a song has the value of "true". However if there is no song playing the attribute doesn't exist at all.
This is the script I currently have and when I am listening to a song via spotify or iTunes etc... it works fine.
<p>
<p class="nowplaying"> <span class="track"></span> by <span class="artist"></span></p>
<p>
<script type="text/javascript">
$.getJSON('https://ws.audioscrobbler.com/2.0/?method=user.getrecenttracks&user=JamesTaylor87&api_key=ADD-API-KEY-HERE&format=json', function(data) {
var artist = $(".artist"),
track = $(".track"),
np = $(".nowplaying"),
artistVal = data.recenttracks.track[0].artist["#text"],
trackVal = data.recenttracks.track[0].name,
nowplaying = data.recenttracks.track[0]["#attr"].nowplaying;
if(typeof nowplaying === "undefined"){
np.prepend("The last song I listened to was")
artist.append(artistVal);
track.append(trackVal);
} else {
np.prepend("I am currently listening to")
artist.append(artistVal);
track.append(trackVal);
}
});
</script>
However when I am not listening to anything I get the following error message (in safari) and nothing works:
undefined is not an object (evaluating 'data.recenttracks.track[0]["#attr"].nowplaying')
in chrome the error is displayed as follows:
Uncaught TypeError: Cannot read property 'nowplaying' of undefined
I have attempted to use an if statement for when it's undefined which hasn't worked and don't really know what else to try. Any help would be much appreciated.

Replace
data.recenttracks.track[0]["#attr"].nowplaying
with
data.recenttracks.track[0]["#attr"] && data.recenttracks.track[0 ["#attr"].nowplaying
That should stop the error occuring if data.recenttracks.track[0]["#attr"] is undefined

Try changing the line where you defined nowplaying to this:
nowplaying = (data.recenttracks.track[0]["#attr"]) ? data.recenttracks.track[0]["#attr"].nowplaying : undefined;
According to the chrome error, data.recenttracks.track[0]["#attr"] is undefined, which means you can't look for a property on it. You can use an if statement or a ternary to check whether this is defined before checking for its nowplaying property.

var attrs = data.recenttracks.track[0]["#attr"];
if (typeof attrs !== 'undefined') {
var nowPlaying = attrs.nowplaying;
}

Try this:
var track = data.recenttracks.track[0];
var nowplaying = track.hasOwnProperty('#attr') && track['#attr'].nowplaying;

I just built a very similar function for my site with Last.fm, and ran into this same problem. I was able to solve the problem by removing subsequent .nowplaying that you've included.
See below. Hope it's helpful!
// get the api
$.getJSON('http://ws.audioscrobbler.com/2.0/?method=user.getRecentTracks&user=YOURUSERNAME&limit=1&api_key=YOURAPIKEY&format=json', function(data) {
var latesttrack = data.recenttracks.track[0]
var trackTitle = latesttrack.name
var trackArtist = latesttrack.artist["#text"]
// detect if the track has attributes associated with it
var nowplaying = latesttrack["#attr"]
// if nowplaying is underfined
if (typeof nowplaying === 'undefined') {
$('.nowplaying').html("Currently listening to nothing.")
} else {
$('.nowplaying p').html("Currently listening to" + trackTitle + " by " + trackArtist)
}
});
See it in action here: http://theadamparker.com/daily

<script type="text/javascript">
//<![CDATA[
var lastfm_api = 'http://ws.audioscrobbler.com/2.0/';
var lastfm_methods = 'user.getRecentTracks';
var lastfm_user = 'YOUR_USERNAME';
var lastfm_key = 'YOUR_APIKEY';
var lastfm_limit = '1';
var lastfm_json = lastfm_api + '?method=' + lastfm_methods + '&user=' + lastfm_user + '&api_key=' + lastfm_key + '&limit=' + lastfm_limit + '&format=json';
$.getJSON(lastfm_json, function(data) {
var html = '';
var song = data.recenttracks.track[0].name,
artist = data.recenttracks.track[0].artist["#text"],
url = data.recenttracks.track[0].url,
cover = data.recenttracks.track[0].image[0]['#text'];
html += '<p>' + song + ' by ' + artist + '<br /><br /><img src="' + cover + '" style="display: block; width: 96px; height: 96px;" /></p><p>Share on Twitter</p>';
$('#recent-tracks').append(html);
});
//]]>
</script>
<div id="recent-tracks"></div>

How to get the value of id of innerHTML?

I have created a html like this:
<body onload = callAlert();loaded()>
<ul id="thelist">
<div id = "lst"></div>
</ul>
</div>
</body>
The callAlert() is here:
function callAlert()
{
listRows = prompt("how many list row you want??");
var listText = "List Number";
for(var i = 0;i < listRows; i++)
{
if(i%2==0)
{
listText = listText +i+'<p style="background-color:#EEEEEE" id = "listNum' + i + '" onclick = itemclicked(id)>';
}
else
{
listText = listText + i+ '<p id = "listNum' + i + '" onclick = itemclicked(id)>';
}
listText = listText + i;
//document.getElementById("lst").innerHTML = listText+i+'5';
}
document.getElementById("lst").innerHTML = listText+i;
}
Inside callAlert(), I have created id runtime inside the <p> tag and at last of for loop, I have set the paragraph like this. document.getElementById("lst").innerHTML = listText+i;
Now I am confuse when listItem is clicked then how to access the value of the selected item.
I am using this:
function itemclicked(id)
{
alert("clicked at :"+id);
var pElement = document.getElementById(id).value;
alert("value of this is: "+pElement);
}
But getting value as undefined.
Any help would be grateful.

try onclick = itemclicked(this.id) instead of onclick = 'itemclicked(id)'

Dude, you should really work on you CodingStyle. Also, write simple, clean code.
First, the html-code should simply look like this:
<body onload="callAlert();loaded();">
<ul id="thelist"></ul>
</body>
No div or anything like this. ul and ol shall be used in combination with li only.
Also, you should always close the html-tags in the right order. Otherwise, like in your examle, you have different nubers of opening and closing-tags. (the closing div in the 5th line of your html-example doesn't refer to a opening div-tag)...
And here comes the fixed code:
<script type="text/javascript">
function callAlert() {
var rows = prompt('Please type in the number of required rows');
var listCode = '';
for (var i = 0; i < rows; i++) {
var listID = 'list_' + i.toString();
if (i % 2 === 0) {
listCode += '<li style="background-color:#EEEEEE" id="' + listID + '" onclick="itemClicked(this.id);">listItem# ' + i + '</li>';
}
else {
listCode += '<li id="' + listID + '" onclick="itemClicked(this.id);">listItem# ' + i + '</li>';
}
}
document.getElementById('thelist').innerHTML = listCode;
}
function itemClicked(id) {
var pElement = document.getElementById(id).innerHTML;
alert("Clicked: " + id + '\nValue: ' + pElement);
}
</script>
You can watch a working sample in this fiddle.
The problems were:
You have to commit the id of the clicked item using this.id like #Varada already mentioned.
Before that, you have to build a working id, parsing numbers to strings using .toString()
You really did write kind of messy code. What was supposed to result wasn't a list, it was various div-containers wrapped inside a ul-tag. Oh my.
BTW: Never ever check if sth. is 0 using the ==-operator. Better always use the ===-operator. Read about the problem here
BTW++: I don't know what value you wanted to read in your itemClicked()-function. I didn't test if it would read the innerHTML but generally, you can only read information from where information was written to before. In this sample, value should be empty i guess..
Hope i didn't forget about anything. The Code works right now as you can see. If you've got any further questions, just ask.
Cheers!

You can pass only the var i and search the id after like this:
Your p constructor dymanic with passing only i
<p id = "listNum' + i + '" onclick = itemclicked(' + i + ')>
function
function itemclicked(id)
{
id='listNum'+i;
alert("clicked at :"+id);
var pElement = document.getElementById(id).value;
alert("value of this is: "+pElement);
}
is what you want?

I am not sure but shouldn't the onclick function be wrapped with double quotes like so:
You have this
onclick = itemclicked(id)>'
And it should be this
onclick = "itemclicked(id)">'
You have to modify your itemclicked function to retrieve the "value" of your p element.
function itemclicked( id ) {
alert( "clicked at :" + id );
var el = document.getElementById( id );
// depending on the browser one of these will work
var pElement = el.contentText || el.innerText;
alert( "value of this is: " + pElement );
}
demo here

JavaScript back button to display previous list

I want create a web application that display a list of items. Suppose I have displayed a list view (say listobject1) of 3 items. when clicked on any of them I get new list view (say listobject2) which its value is according to listobject1. When again I click one of them I get another view. Now when I click back button i want to go back to previous list view i.e. when I'm now on listobject2 and again when back button is pressed I want to show listobject1. Can anybody tell me how I can do this in JavaScript?
Edit
I'm still study about the stuff but I can't solve this problem yet. In order to clarify my problem now, here's my code:
$(document).ready(function() {
$("#result").hide();
$("input[name='indexsearch']").live("click", function() {
$("#result").show();
$("#result").empty();
loading_img();
var $textInput = $("[name='valueLiteral']").val();
$.getJSON("get_onto", {
"input" : $textInput
}, function(json) {
if(json.length > 0 ) {
var arrayPredicate = [];
var arrayObject = [];
var arraySubject = [];
$.each(json, function(index, value) {
arraySubject[index] = value.subject;
arrayPredicate[index] = value.predicate;
if(value.objectGeneral != null) {
arrayObject[index] = value.objectGeneral;
} else {
arrayObject[index] = value.objectLiteral;
}
}
);
var stmt = [];
//concat all related array into string (create triple statement)
$.each(arrayPredicate, function(k,v){
stmt[k] = "<span class='subject' id="+arraySubject[k]+">"
+ arraySubject[k] + "</span> " + " -> " + v + " : "+
//change object from text to be button form
"<button class = 'searchAgain-button' name = 'searchMore' \n\
value = " + arrayObject[k] + ">" + arrayObject[k] + "</button><br> <br>";
});
stmt = stmt.sort();
$.each(stmt, function(k,v){
$("#result").append(v);
});
} else {
var $noresult = "No Result : Please enter a query";
$("#result").append($noresult);
}
});
});
$("button").live("click", function() {
$("#result").show();
$("#result").empty();
loading_img();
var $textInput = $(this).attr("Value");
//var $textInput = "G53SQM";
$.getJSON("get_onto", {
"input" : $textInput
}, function(json) {
if(json.length > 0 ) {
var arrayPredicate = [];
var arrayObject = [];
var arraySubject = [];
$.each(json, function(index, value) {
arraySubject[index] = value.subject;
arrayPredicate[index] = value.predicate;
if(value.objectGeneral != null) {
arrayObject[index] = value.objectGeneral;
} else {
arrayObject[index] = value.objectLiteral;
}
}
);
var stmt = [];
var searchMore = "searchMore";
//concat all related array into string (create triple statement)
$.each(arrayPredicate, function(k,v){
stmt[k] = "<span class='subject' id="+arraySubject[k]+">" + arraySubject[k] + "</span> " + " -> " + v + " : "+ " <button class = 'searchAgain-button' name = " +searchMore + " value = " + arrayObject[k] + ">" + arrayObject[k] + "</button><br><br>";
});
stmt = stmt.sort();
$.each(stmt, function(k,v){
$("#result").append(v);
});
} else {
var $noresult = "No Result : Please enter a query";
$("#result").append($noresult);
}
});
});
At first, user only see one button name "valueLiteral". After user perform 1st search, the result is return in a form of JSON and eventually put in stmt[] to display, which at this state the second button was create as a clickable-result which will automatically take the value of result and do second search if user click the second button.
Now the problem is, I want to add a 3rd HTML button name "back" to make the web display the previous result in stmt[] if user click on the button.
Hope this helps in clarify the problems, I'm still doing a hard work on this stuff since I'm a newbie in JavaScript. Appreciate all helps.

This is what you want almost exactly the way you want it.
You'll have to use history.pushState to push these fake events into the history.
Alternatively, you can use location.hash to store the current object, and update the hash every time you display a new list. Then onhashchange find the hash and display the appropriate list.

See http://jsfiddle.net/cFwME/
var history=[new Array(),new Array()];
history[0].id="#back";
history[1].id="#next";
Array.prototype.last=function(){
return this[this.length-1];
}
$('#list>li:not(:first)').click(function(){
if(!history[0].length || history[0].last().html()!=$('#list').html()){
history[0].push($('#list').clone(true,true));
$(history[0].id).prop('disabled',false);
history[1].length=0;
$(history[1].id).prop('disabled',true);
}
$('#list>li:first').html('This is List '+$(this).index());
});
$('#back').click(getHistory(0));
$('#next').click(getHistory(1));
function getHistory(n){
return function(){
if(!history[n].length){return false;}
history[(n+1)%2].push($('#list').replaceWith(history[n].last()));
history[n].pop();
$(history[(n+1)%2].id).prop('disabled',false);
if(!history[n].length){$(history[n].id).prop('disabled',true);}
}
}

Check out jQuery BBQ - http://benalman.com/projects/jquery-bbq-plugin/

the javascript template and the event handling

I have asked a question about how to avoiding to write the html in the js,then some people tell me using the javascript template,for example,the jquery/template pugin and ect.
It is a good idea when generate static html,for example:
<ul id="productList"></ul>
<script id="productTemplate" type="text/x-jquery-tmpl">
<li><a>${Name}</a> (${Price})</li>
</script>
<script type="text/javascript">
var products = [
{ Name: "xxx", Price: "xxx" },
{ Name: "yyy", Price: "xxx" },
{ Name: "zzz", Price: "xxx" }
];
// Render the template with the products data and insert
// the rendered HTML under the "productList" element
$( "#productTemplate" ).tmpl( products )
.appendTo( "#productList" );
</script>
However when I try to bind some event to the generated html,I meet some problem.
For example,I have a page which user can search some products by the price/name/location.
So I have three function:
searchByPrice(lowPrice,highPrice,productType,currentPage)
searchByName(name,productType,currentPage);
searchByLocation(location,currentpage);
ALl the above function have a realated method in the server side and they will retrun the products usint the xml format.
Since they will retrun so many items,so I have to paging them,the "currengPage" is used to tell the server side which part of results should be returned.
When the client get the result from the server side,now it is the js for display them int he div and create a Paging Bar if possible.
Before I know the template,I use this manner(which I hate most,try my best to avoid):
function searchByPrice(lowPrice,highPrice,productType,currentPage){
var url="WebService.asmx/searchByPrice?low="+lowPrice="&high="+highPrice+"&curPage="+currentPage;
//code to create the xmlHttp object
xmlhttp.open("GET",url,true);
xmlhttp.onreadystatechange=function(){
if (xmlhttp.readyState==4 && xmlhttp.status==200){
var i=0;
var Prohtml="";
var proList=parseProductList(xmlhttp.responseText);
for(i=0;i<prolist.length;i++){
Prohtml+="<li><a href='#'>"+prolist[i].name+"</a> ("+prolist[i].price"+)</li>";
}
//generate the paging bar:
var totleResult=getTotleResultNumber(xmlhttp.responseText);
if(totleResult>10){
var paghtml="<span>";
//need the paging
var pagNum=totleResult/10+1;
for(i=1;i<=pagenum;i++){
paghtml+="<a onclick='searchByPrice(lowPrice,highPrice,productType,currentPage+1)'>i</a>";
//here the synax is not right,since I am really not good at handle the single or doule '"' in this manner.
//also if in the searchByName function,the click function here should be replaced using the searchByName(...)
}
}
}
}
}
In the example,it is easy to use the template to generate the "Prohtml" since there is no event handling with them,but how about the "paghtml",the click function is different in differnt search type.
So,any good idea to hanld this?

Either:
Create DOM Elements instead of building HTML strings, using document.createElement or a small library if you're doing lots of this, which will allow you to attach events immediately in the usual fashion.
or
Give each element which needs to make use of event handlers a unique ID and build up a list of events to be attached once the HTML has been inserted into the document.
E.g.:
var eventHandlers = []
, eventCount = 0;
for (i = 1; i <= pagenum; i++) {
var id = "search" + eventCount++;
html += "<a id='" + id + "'>" + i + "</a>";
eventHandlers.push([id, 'click',
handler(searchByPrice, lowPrice, highPrice, productType, currentPage + i)])
}
// Later...
someElement.innerHTML = html;
registerEvents(eventHandlers);
Where registerEvents is:
function registerEvents(eventHandlers) {
for (var i = 0, l = eventHandlers.length; i < l; i++) {
var eventHandler = eventHandlers[i],
id = eventHandler[0],
eventName = eventHandler[1],
func = eventHandler[2];
// Where addEvent is your cross-browser event registration function
// of choice...
addEvent(document.getElementById(id), eventName, func);
}
}
And handler is just a quick way to close over all the arguments passed in:
/**
* Creates a fnction which calls the given function with any additional
* arguments passed in.
*/
function handler(func) {
var args = Array.prototype.slice.call(arguments, 1);
return function() {
func.apply(this, args);
}
}
I use something like this approach (but automatically adding unique ids when necessary) in the HTML generation portion of my DOMBuilder library, which offers a convenience method for generating HTML from content you've defined, inserting it into a given element with innerHTML and registering any event handlers which were present. Its syntax for defining content is independent of output mode, which allows you to switch between DOM and HTML output seamlessly in most cases.

First of all, you can simply use the $.get() or $.ajax() for your AJAX call.
Secondly, you can use .live() or .delegate() to bind events to elements that do not exist.
Thirdly, you can use the data attributes in the anchor elements as a way to pass in the arguments for the event handler, see .data().
So, to rewrite your function, you have may something like the following:
function searchByPrice(event) {
$this = $(this);
var lowPrice = $this.data('lowPrice'),
highPrice = $this.data('lowPrice'),
productType = $this.data('productType'),
currentPage = $this.data('currentPage');
var url = "WebService.asmx/searchByPrice?low=" + lowPrice = "&high=" + highPrice + "&curPage=" + currentPage;
$.get(url, function(data, textStatus, jqXHR) {
var i = 0;
var Prohtml = "";
var proList = parseProductList(data);
for (i = 0; i < prolist.length; i++) {
Prohtml += "<li><a href='#'>" + prolist[i].name + "</a> (" + prolist[i].price "+)</li>";
}
//generate the paging bar:
var totleResult = getTotleResultNumber(data);
if (totleResult > 10) {
var paghtml = "<span>";
//need the paging
var pagNum = totleResult / 10 + 1;
for (i = 1; i <= pagenum; i++) {
paghtml += '<a class="pagelink" ' +
'data-lowPrice="' + lowPrice + '" ' +
'data-highPrice="' + highPrice + '" ' +
'data-productType="' + productType + '" ' +
'data-currentPage="' + (currentpage + 1) + '">' + i + '</a>';
//here the synax is not right,since I am really not good at handle the single or doule '"' in this manner.
//also if in the searchByName function,the click function here should be replaced using the searchByName(...)
}
}
});
}
$(document).ready(function(){
$("a.pagelink").live('click', searchByPrice);
});