If var not set always results in true, even if its set - javascript

Not sure how to formulate this but here it goes.
I am checking if a var exists (content), if it doesnt i set it.
Problem is next click, it still behaves as if there is no var content. But why??
Here my code:
$("#nav a").click(function(event) {
event.preventDefault();
var href = $(this).attr("href");
var load = href + " .content";
if (!content)
{
var content = $('<div>').load(load);
$(".content").append(content);
}
else
{
var position = content.offset();
$(document).scrollTop(position);
}
});
It never results to else, so always a click is made the whole load and append function repeats.
Basically how can I record that content for this particular link has been loaded once, so the else function should be performed next time?
Also, what is wrong with my if(!content) statement? Is it because of scope?

In Javascript functions determine the scope of an object. You need to place content in the global scope. Currently it is created within the anonymous function assigned to the click event handler, so when the function is executed again content is out of scope causing it to return false.
var content;
$("#nav a").click(function(event) {
event.preventDefault();
var href = $(this).attr("href");
var load = href + " .content";
if (!content)
{
content = $('<div>').load(load);
$(".content").append(content);
}
else
{
var position = content.offset();
$(document).scrollTop(position);
}
});

Try to make the var content as a global variable rather than a local one, like you are doing right now. That's why the if (!content) result as true always, like:
var content;
$("#nav a").click(function (event) {
event.preventDefault();
var href = $(this).attr("href");
var load = href + " .content";
if (!content) {
content = $('<div>').load(load);
$(".content").append(content);
} else {
$(document).scrollTop(content.offset());
}
});
Just to show what happens, when value of content is not set at first and then set again:
var content;
console.log(content); // undefined
console.log(!content); // true
content = 'text';
console.log(content); // text
console.log(!content); // false

Thanks to everyone for answering the first question about the checking if var exists.
I ended up ditching this whole concept it turned out the
one()
function is what I needed all along. In order to only execute a function once and another function on all following clicks.
Here it is:
$(document).ready(function() {
//Ajaxify Navi
$("#nav a").one("click", function(event) {
event.preventDefault();
var href = $(this).attr("href");
var load = href + " .content";
var content = $('<div>').load(load);
$(".content").append(content);
$(this).click(function(event) {
event.preventDefault();
var position = content.offset().top;
$(document).scrollTop(position);
$("body").append(position);
});
});
});
What this is is the following:
1st click on a button loads content via ajax and appends it, second click on the same button only scrolls to said content.

Related

Store div status on page reload

I have multiple divs in one html page under common wrapper class.
I am using hide and show method on clicking next and previous option.
What I am trying to achieve: On page reload/refresh, the div which is showing currently should show after page reload.
So in short if you reload/refresh from pink screen, it should show same pink screen after page reload.
What I tried: I am storing the display properties (none or block) is local storage and on page reload trying to give same properties to divs again. Most of the responses and solution I checked in Stack overflow is regarding opening the same tab when refresh. but my case is what in same tab I have multiple div and I want to open from the same state which it was earlier.
Logic I used:
$(window).on('load', function(){
var disp = localStorage.getItem("disp");
var ustatus = JSON.parse(disp);
$(".chk").text(ustatus);
for (var x=ustatus; x<ustatus.length; x++){
$(".pg"+x).css("display", ustatus[x]);
}
});
This is fiddle link I tried:
Page reload demo JS Fiddle link
Your HTML and CSS code is perfect but you need to make corrections in your JavaScript code.
Observation 1 : You "for" loop to assign display style has problem with variable x. You need to assign integer value to x.
Observation 2 : You need to remove that "display" style from "div" elements when you click on "next" and "previous" links.
Hear is new Js fiddle link with updated code.
$(window).on('load', function () {
//localStorage.removeItem("disp");
var disp = localStorage.getItem("disp");
var ustatus = JSON.parse(disp);
$(".chk").text(ustatus);
for (var x = 1; x <= ustatus.length; x++) {
$(".pg" + x).css("display", ustatus[x-1]);
}
});
$(".next").on("click", function () {
$(this).parent().addClass("off").removeClass("on").removeAttr("style");
$(this).parent().next().addClass("on").removeClass("off").removeAttr("style");
});
$(".prev").on("click", function () {
$(this).parent().addClass("off").removeClass("on").removeAttr("style");
$(this).parent().prev().addClass("on").removeClass("off").removeAttr("style");
});
$(window).on('beforeunload', function () {
var display = $(".clr").map(function () {
return $(this).css("display");
}).get();
localStorage.setItem("disp", JSON.stringify(display));
});
You can also download this file. Please run index.html to see the output.
You don't really need the on class:
$(window).on('load', function(){
var disp = localStorage.getItem("disp");
var ustatus = JSON.parse(disp);
$(".chk").text(ustatus);
for (var x=0; x<ustatus.length; x++){
$(".pg"+(x+1)).toggleClass("off", ustatus[x]);
}
});
$(".next").on("click", function(){
$(this).parent().addClass("off");
$(this).parent().next().removeClass("off");
});
$(".prev").on("click", function(){
$(this).parent().addClass("off");
$(this).parent().prev().removeClass("off");
});
$(window).on('beforeunload', function(){
var display = $(".clr").map(function(){
return $(this).hasClass("off");
}).get();
localStorage.setItem("disp", JSON.stringify(display));
});
Fiddle
note: you can't use $(window).on('load', ...) in a fiddle - the JS in the editor is run on load
EDIT: you might also want to validate ustatus before applying it, something like
if (Array.isArray(ustatus) && ustatus.filter(x => x === true).length === 1) {
for (var x=0; x<ustatus.length; x++){
$(".pg"+(x+1)).toggleClass("off", ustatus[x]);
}
}
You can do it without using display, you can use on and off classes, i think that's why they are created for
$(window).on('load', function(){
var disp = localStorage.getItem("disp");
var ustatus = JSON.parse(disp);
if(ustatus!=undefined){
$(".chk").text(ustatus);
for (var x=1; x<=ustatus.length; x++){
if(ustatus[x-1]=='on'){
$(".pg"+x).addClass("on").removeClass("off");
}
else{
$(".pg"+x).addClass("off").removeClass("on");
}
}
}
$(".next").on("click", function(){
$(this).parent().addClass("off").removeClass("on");
$(this).parent().next().addClass("on").removeClass("off");
});
$(".prev").on("click", function(){
$(this).parent().addClass("off").removeClass("on");
$(this).parent().prev().addClass("on").removeClass("off");
});
$(window).on('beforeunload', function(){
var display = $(".clr").map(function(){
if($(this).hasClass('on'))
return 'on';
else
return 'off';
}).get();
localStorage.setItem("disp", JSON.stringify(display));
});
});

modify url by clicking a div

I have a page in php, and I'm trying to add an ?id=variable_value extension to it's url when I click on a div, but when I click it gives me an undefined url error with the extension
Here is the script:
<script language="javascript" type="text/javascript">
var Pokemon_ID = 1;
function changeUrl() {
location.href=this.href+'?id='+Pokemon_ID;return false;
}
document.getElementById( 'right-btn' ).onclick = function() {
changeUrl();
};
</script>
And the div :
<div id="right-btn" href="pokedex.php" onclick="changeUrl()">
Don't use two separate ways of attaching handlers when you only need one. Inline event handlers are essentially eval inside HTML markup - they're bad practice and result in poorly factored, hard-to-manage code. Seriously consider attaching your events with JavaScript, instead.
The problem is that when assigning the handler via onclick, the this in changeUrl is undefined, because the calling context is global. Feel free to avoid using this when it can cause confusion.
Just use addEventListener alone. Also, you'll have to use getAttribute('href') instead of .href because divs are not supposed to have href properties.
const Pokemon_ID = '5';
document.getElementById('right-btn').addEventListener('click', function(e) {
// location.href = e.target.getAttribute('href') + '?id=' + Pokemon_ID;
console.log('changing URL to ' + e.target.getAttribute('href') + '?id=' + Pokemon_ID);
});
<div id="right-btn" href="pokedex.php">text</div>
Try this instead:
location.href += '?id=' + Pokemon_ID;
Because you call changeUrl() within the onclick method you loose the context of this. This in changeUrl is not your div. Maybe you have to pass this into the method with changeUrl(this) or you just pass the href with changeUrl(this.href).
Than use:
function changeUrl(target){
location.href=target.href+'?id='+Pokemon_ID;
}
As mentioned by CertainPerformance above, you are not passing the right arguments to you function to work correctly; Using you code as a reference, you can either pass the original event to you changeUrl() function, then use the e.target to get to your 'right-btn' element.
Javascript:
var Pokemon_ID = 1;
function changeUrl(e) {
var href = e.target.getAttribute('href');
console.log(href +'?id=' + Pokemon_ID);
return false;
}
document.getElementById( 'right-btn' ).onclick = function(e) {
changeUrl(e);
};
HTML:
<div id="right-btn" href="pokedex.php">Click Me 4</div>
However, if you realy want to use this in your function to refer to the 'right-btn' element, then you can change the code to;
Javascript:
var Pokemon_ID = 1;
function changeUrl() {
var href = this.getAttribute('href');
console.log(href +'?id=' + Pokemon_ID);
return false;
}
document.getElementById( 'right-btn' ).onclick = function(e) {
changeUrl.call(e.target);
};
The changes being the call in the event handler:
changeUrl.call(e.target);, which calls you function in the 'context' of the e.target, making the this in your changeUrl() function to the element. Then you can use the this as in var href = this.getAttribute('href');

addEventListener won't work because of null

All I'm trying to do is have the user click the button, and when that event occurs I want an image to display within a div. I inspected the element, and it says that tableButton is undefined, but I defined it right before the addEventListener. What am I doing wrong? Sorry, I'm new to javascript.
function openTable() {
var code = "<img src='PeriodicTableOfElements.png'>";
var periodic = document.getElementById("Periodic");
periodic.innerHTML = code;
}
var tableButton = document.getElementById("openTable");
tableButton.addEventListener("click", openTable, false);
Have you made sure to wrap it in window.onload, elements can't exist if the window hasn't loaded.
window.onload = function(){
function openTable() {
var code = "<img src='PeriodicTableOfElements.png'>";
var periodic = document.getElementById("Periodic");
periodic.innerHTML = code;
}
var tableButton = document.getElementById("openTable");
tableButton.addEventListener("click", openTable, false);
}

Rest .next()? My click function adding '.active' twice?

If you take a look at this fiddle it will seem fine, but if you click next and move down 2 to 3 times, and then click "memory" (in top nav) it takes .active back to the first .item,
then if you click 'NEXT' again it continues to go to the next element from the prior one we left off of.
I am trying to reset it and continue based on where we go after clicking on the top nav.
Faulty jQuery:* Two click functions both adding active*
var items = $('.item'),
currentItem = items.filter('.active'),
last = items.last();
$("#next-button").on('click', function () {
currentItem.removeClass('active');
var nextItem = currentItem.next();
if (nextItem.length) {
currentItem = nextItem.addClass('active');
if (currentItem.is(last)) {
$('#slide-buttons').addClass('red');
}
}
var items = $('.item');
$(".breadcrumb-cell .breadcrumb").click(function () {
var theID = $(this).data("id");
items.filter(function() {
return $(this).data('category') === theID;
}).addClass('active');
});
});
Fiddle
I Googled "how to reset .next() jquery" but couldn't find anything, not sure if that's even the right thing to do?
The problem you had was that currentItem didn't get updated when you clicked on a breadcrumb.
I made a lot of changes, mostly "streamlining" things. I removed your global variables and based the current item on the active class instead. Check: http://jsfiddle.net/kQabJ/17/
$("#next-button").on('click', function () {
var nextItem = $('.active').removeClass('active').next();
if (!nextItem.length) {
nextItem = $('.item').first();
}
nextItem.addClass('active');
});
$(".breadcrumb-cell .breadcrumb").on('click', function () {
$('.active').removeClass('active');
var theID = $(this).data("id");
$("#" + theID).addClass('active');
});
Note that I also modified your DOM a bit to make it easier to select an item when a user clicks a breadcrumb. That change is using an ID on your .items instead of data. This way you can do $("#" + theID) rather than filtering based on data.
Since these things are uniquely identifying your .item elements themselves - it makes since to use an id anyway, but if this is not what you not you can always change that part back.
You just need to update currentItem, see http://jsfiddle.net/kQabJ/13/
$(".breadcrumb-cell .breadcrumb").on('click', function () {
items.removeClass('active');
var theID = $(this).data("id");
items.filter(function() {
return $(this).data('category') === theID;
}).addClass('active');
currentItem = items.filter('.active');
});
Try this code
You were not updating the currentItem, which was causing the problem.
var items = $('.item'),
currentItem = items.filter('.active'),
last = items.last();
$("#next-button").on('click', function () {
currentItem = items.filter('.active');
var nextItem = currentItem.next();
currentItem.next().length > 0 ? currentItem.next().addClass('active')
: items.first().addClass('active');
currentItem.removeClass('active');
});
$(".breadcrumb-cell .breadcrumb").on('click', function () {
items.removeClass('active');
var theID = $(this).data("id");
items.filter(function () {
return $(this).data('category') === theID;
}).addClass('active');
});
Check Fiddle

jQuery getting ID of clicked link

I have a modal box in jQuery which I have created to display some embed code. I want the script to take the id of the link that is clicked but I can't seem to get this working.
Does anyone know how I can do that or why this may be happening?
My jQuery code is:
function generateCode() {
var answerid = $('.openembed').attr('id');
if($('#embed input[name="comments"]:checked').length > 0 == true) {
var comments = "&comments=1";
} else {
var comments = "";
}
$("#embedcode").html('<code><iframe src="embed.php?answerid=' + answerid + comments + '" width="550" height="' + $('#embed input[name="size"]').val() + '" frameborder="0"></iframe></code>');
}
$(document).ready(function () {
$('.openembed').click(function () {
generateCode();
var answerid = $('.openembed').attr('id');
$('#box').show();
return false;
});
$('#embed').click(function (e) {
e.stopPropagation()
});
$(document).click(function () {
$('#box').hide()
});
});
My mark-up is:
Embed
Embed
Your problem is here:
$('.openembed')
returns an array of matched elements. Your should instead select only the clicked element.
$('.openembed') works correctly if you assing a click event to all elements that have this class. But on the other hand, you're unable do know which is clicked.
But fortunately in the body of handler function click you could call $(this).
$(this) will return the current (and clicked element).
// var answerid = $('.openembed').attr('id'); // Wrong
var answerid = $(this).attr('id'); // Correct
// Now you can call generateCode
generateCode(answerid);
Another error is the body of generateCode function. Here you should pass the id of selected element. This is the correct implementation.
function generateCode(answerid) {
if($('#embed input[name="comments"]:checked').length > 0 == true) {
var comments = "&comments=1";
} else {
var comments = "";
}
$("#embedcode").html('<iframe src="embed.php?answerid=' + answerid + comments + '" width="550" height="' + $('#embed input[name="size"]').val() + '"frameborder="0"></iframe>');
}
Here I have implemented your code with the correct behavior: http://jsfiddle.net/pSZZF/2/
Instead of referencing the class, which will grab all members of that class, you need to reference $(this) so you can get that unique link when it is clicked.
var answerid = $(this).prop('id');
$('.openembed').click(function () {
generateCode();
var answerid = $(this).attr('id');
$('#box').show();
return false;
});
Use $(this). $('.openembed') refers to multiple links.
var answerid = $('.openembed').attr('id');
needs to be
var answerid = $(this).prop('id');
The other answers are trying to fix the click() function, but your issue is actually with the generateCode function.
You need to pass the clicked element to the generateCode function:
$('.openembed').click(function () {
generateCode(this);
And modify generateCode:
function generateCode(element) {
var answerid = element.id;
Of course var answerid = $('.openembed').attr('id'); within the click code isn't correct either, but it doesn't seem to do anything anyway.
Get the id when the correct anchor is clicked and pass it into your generateCode function
$('.openembed').click(function () {
var answerid = $(this).attr('id');
generateCode(answerid)
$('#box').show();
return false;
});
Change your function
function generateCode(answerid) {
// dont need this line anymore
// var answerid = $('.openembed').attr('id');

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