Undefined DOM element javascript, while console.log gives it out - javascript

I'm quite new in javascript and this problem is haunting me down since the very begining. When I get DOM element event behaves properly, but while I try to change anything (like class) it gives me "undefined is not a function".
I don't understand why, because in the same time console.log gives out
<div class="nav-about menu" id="nav-about"></div>
HTML
<div class="nav-about menu" id="nav-about"></div>
JS
var link_one = document.getElementById("nav-about");
link_one.addEventListener("click", function(){
console.log(this);
this.addClass('special');
}, false);
I couldn't find answer to that anywhere. Yes jquery to addClass is included in head tag.

Because there is no addClass property on this, so it's undefined.
You could add the class on this.classList.
var link_one = document.getElementById("nav-about");
link_one.addEventListener("click", function(){
this.classList.add('special');
}, false);

try
$(this).addClass('special');
because you want to use jquery library, to use jquery library is like calling a function doSomething(this), but instead use $ as the function name

Related

How to fix jQuery DOM using Object problem

I am trying to set an id in html to a string set that is located inside a property inside an object using jquery. But for some reason, when I do run the program, the jquery script doesn't work. I tried setting the html DOM code inside the document.ready, and also tried to run the code inside a function that runs after other events are activated but nothing changed. Help me fix this problem.
$(document).ready(function() {
var testObj = {
exampleText = "Hello world"
};
$("#test").html(testObj.exampleText);
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/jquery/3.3.1/jquery.min.js"></script>
<p id="test"></p>
You have a syntax error.
use var testObj = {exampleText: "Hello world"}; instead.

Mouse Events on JsFiddle not working?

I've got my fiddle here, but I can't understand why it's not calling my function on the 'onmouseout' event.
http://jsfiddle.net/foreyez/Xf6LW/
any ideas?
Works fine, you just needed to put the function in the head (or body after the element is in the DOM) of the document.
jsFiddle example
It's because the functions you create in the JavaScript panel are not global when you have the onLoad option selected. Your JavaScript gets wrapped in a function.
If you do want them to be global you have to either do what j08961 suggested, by changing that dropdown to say no wrap (body or head) will work
The best solution would be to not set your event handlers from HTML, that's bad practice anyway, then you're not relying on global functions or mixing HTML and JS.
<div id="myDiv">
</div>​
document.getElementById('myDiv').onmousemove = function() {
alert('here');
}
Side note: you should have noticed the error in the console saying that myFunc is undefined or something like it.
I think it's cause for jsfiddle, it declares all the javascript AFTER the HTML. The HTML is going to run and look for a myFunc and not find it. Then it's going to load the JS and it won't even run it.
Here you can see the changes : jsfiddle.
make myFunc as a global function;
I searched my code using firebug and got following generated code.
window.addEvent('load', function() {
//window.myFunc makes myFunc as a global function
// It can be accessed from any were inside current window.
window.myFunc = function myFunc(x)
{
alert('yo');
}
// function below is not available gloably.
function myFunct1(){
alert('yo1');
}
});
see jsfiddle

Set onclick of <a> using JavaScript

I want to change all the links in a div such that they no longer refer to a page, but run a JavaScript function when being clicked. To do so, I wrote this function:
function buildPageInDiv(htmlString){
console.log(typeof htmlString);
$div = $(htmlString).children("div#myDiv");
$div.children("a").each(function(i, element){toJavascriptLinks(element)});
document.getElementById("targetDiv").innerHTML = $div[0].innerHTML;
}
calling this function:
function toJavascriptLinks(element){
element.href="#";
element.onclick = function(){console.log('Yeah!')};
console.log(element);
}
Now, when I run buildPageInDiv, 'string' is printed on the console, all the "href" are changed to "#" and for every <a> within the div the console prints the element:
<a href="#">
No sign of the onclick here, and clicking on the link does not show anything on the console.
What am I missing here?
Edit:
I was seeking in the wrong place. The problem was that I was running toJavascriptLinks(element) before attaching the innerHTML to targetDiv. That was no problem for the href attribute, but it was for the onclick attribute. Solution is simply to put it in targetDiv first and than run toJavascriptLinks(element) on targetDiv :
function buildPageInDiv(htmlString){
console.log(typeof htmlString);
var content = $(htmlString).children("div#myDiv")[0].innerHTML;
document.getElementById("targetDiv").innerHTML = content;
$("div#targetDiv").children("a").each(function(i, element) toJavascriptLinks(element)});
}
Although the problem was not in the code I originally posted, the comprehensive answers below led me to the solution.
First: All type of selectors in jQuery, start with the dollar sign and parentheses: $()
Secondly: you need to close your statements with ;
Lastly: it is good practice to define your functions BEFORE you call them, instead of relying on javascript to hoist them to the top for you. This will also make jslint validate, whereas the other way round wouldn't!
So your code without your errors would look like:
function toJavascriptLinks(element){
element.href="#";
element.onclick = function(){alert('Yeah!');};
console.log(element);
}
$('div').children("a").each(function(i, element){toJavascriptLinks(element);});
See this fiddle for a working demo.
Good Luck!!
ABOUT YOUR UPDATED QUESTION:
That's quite an update to your question.
You don't see your onclick in console.log because you set the onclick event in the dom. If you wanted to see the onclick in console.log, you would add the function STRING using:
element.setAttribute('onclick', 'your function string');
Suppose in your html you have:
<a id="link_a" href="http://www.google.com">link 1</a>
<a id="link_b" href="http://www.duckduckgo.com">link 2</a>
And you have this javascript:
var lnkA=document.getElementById("link_a");
var lnkB=document.getElementById("link_b");
lnkA.onclick=function(){alert(this.innerHTML);};
lnkB.setAttribute('onclick','alert(this.innerHTML);');
console.log(lnkA.outerHTML);
console.log(lnkB.outerHTML);
Then console.log will contain:
<a id="link_a" href="http://www.google.com">link 1</a>
<a onclick="alert(this.innerHTML);" id="link_b" href="http://www.duckduckgo.com">link 2</a>
See this fiddle for a live example of this explanation.
I also think you are already using some form of jQuery (without you knowing it) because of your use of .children("div#myDiv"). To my knowledge this no plain vanilla javascript. And I think both plain vanilla javascript and jQuery would not select those divs with id 'myDiv' out of a plain html-string, so the code in your update would not do the job.
Finally, to adjust my answer to your updated question and expectation of the onclick-event being visible in the parsed html-source:
var htmlString='<div id="myDiv">link 1link 2</div><div id="otherDiv">link 3link 4</div>';
function toJavascriptLinks(element){
element.href="#";
element.setAttribute('onclick','console.log("Yeah!");');
console.log(element.outerHTML);
}
//no innerHTML on documentFragment allowed, yet on it's children it's allowed
var frag = document.createDocumentFragment().appendChild( document.createElement('div') );
frag.innerHTML=htmlString;
var $div = $(frag).children('div#myDiv');
$($div).children("a").each(function(i, element){toJavascriptLinks(element);});
var outp=document.getElementById("output");
outp.innerHTML=frag.innerHTML;
See this updated fiddle to see it in action.
That leaves the question: why on earth are you placing 'ninja' $-signs front of your variable names?
That's just the way the debugger displays an HTML element. It doesn't show all attributes - especially since you are setting the DOM property onclick to a function reference, which can't be displayed as the HTML attribute onclick which takes a string (which AFAIK can't be set with JavaScript see Luc's comment).
Try console.log(element.onclick); instead, it should display something like function() {...}.
Or doesn't the event handle work?
BTW, any reason you don't use jQuery to set the href and the handler?
$div.children("a").attr('href', '#').click(function(){console.log('Yeah!')});
One more thing: In most consoles you can click on <a href="#"> and it will display the DOM properties, which should include the event handler.
I would really use jQuery for this, it's quite simple.
​$(function() {
$("div > a ").attr("href", "#").click(function(e) {
e.preventDefault();
doSomething();
});
});
var doSomething = function() {
alert("Woah, it works!");
}
See the following jsfiddle for it in action: http://jsfiddle.net/SsXtt/1/
Are you sure the element is correct? This works for me.
<a id="mylink">Test</a>
<script>
document.getElementById("mylink").onclick = function() {
alert("Works");
};
</script>
Function needs to be inside a string, try adding quotes?

javascript onclick failing on a function call

I have this html...
<a onclick="search.analysisSelect('2');" href="javascript:void(0);">A Product</a>
...And whenever I click that link in the browser (IE, FF, and Chrome), it fails. It tells me that the function does not exist. However, if I type that exact function call into the console of firebug, it runs fine. So the function does exist.
Exact error message: "search.analysisSelect is not a function"
I have recently changed the "search" object name to "searchTab" and the onclick works fine.
Why is the onclick failing for the search object? I am baffled...
Here is the search object. This is stored in a separate js file loaded when the page loads.
var search = {
analysisSelect: function(pub) {
$("#tabs").tabs("select", "#analysis");
analysisGrid.refreshSlickGrid(pub, '0', '1', '0');
}
};
Oh, I forgot to mention that I also have an init() funciton defined in the search object, which is called on an onclick event for another html element, and that fires off with no issues. Wtf...
Where did you define search.analysisSelect()? It should be defined before the anchor tag.
generally using inline javascripts is not a good idea, consider using an external javascript file and bind that function to the anchor onclick event like this:
window.onload = function() { // ensures that the document is loaded before finding the anchor element
// assign an Id to the anchor tag like this: <a id="idOfAnchorTag" href="#">A Product</a>
var elem = getElementById('idOfAnchorTag');
elem.onclick = function() {
search.analysisSelect('2');
}
}
There is some strange javascript voodoo going on in the inline event handler. search is not being resolved to window.search, it is hitting something else and I don't know what it is.
See http://jsfiddle.net/yPhZ8/
However, I can tell you how to fix it. Use window.search instead.
<a onclick="window.search.analysisSelect('2');" href="javascript:void(0);">A Product</a>
See: http://jsfiddle.net/yPhZ8/1/
I just had this exact problem today. Turns out, you can't have an HTML element with an ID the same as the function.
Don't ask me why, I'd just say it has something to do with extremely lazy parsing.
My Example:
<dd style="margin-left: 2px;"><input type="button" name="info[add_benefit]" id="add_benefit" value="{L_ADD_BENEFIT}" class="button2"
style="width: 100%;" onclick="add_benefit();" /> </dd>
The onclick method would return an error saying that the function didn't exist. Apparently it thought the button itself was the function, but the button was a button, hence the error.

JavaScript: changing the value of onclick with or without jQuery

I'd like to change the value of the onclick attribute on an anchor. I want to set it to a new string that contains JavaScript. (That string is provided to the client-side JavaScript code by the server, and it can contains whatever you can put in the onclick attribute in HTML.) Here are a few things I tried:
Using jQuery attr("onclick", js) doesn't work with both Firefox and IE6/7.
Using setAttribute("onclick", js) works with Firefox and IE8, but not IE6/7.
Using onclick = function() { return eval(js); } doesn't work because you are not allowed to use return is code passed to eval().
Anyone has a suggestion on to set the onclick attribute to to make this work for Firefox and IE 6/7/8? Also see below the code I used to test this.
<html>
<head>
<script type="text/javascript"
src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.2/jquery.js"></script>
<script type="text/javascript">
$(document).ready(function(){
var js = "alert('B'); return false;";
// Set with JQuery: doesn't work
$("a").attr("onclick", js);
// Set with setAttribute(): at least works with Firefox
//document.getElementById("anchor").setAttribute("onclick", js);
});
</script>
</head>
<body>
Click
</body>
</html>
You shouldn't be using onClick any more if you are using jQuery. jQuery provides its own methods of attaching and binding events. See .click()
$(document).ready(function(){
var js = "alert('B:' + this.id); return false;";
// create a function from the "js" string
var newclick = new Function(js);
// clears onclick then sets click using jQuery
$("#anchor").attr('onclick', '').click(newclick);
});
That should cancel the onClick function - and keep your "javascript from a string" as well.
The best thing to do would be to remove the onclick="" from the <a> element in the HTML code and switch to using the Unobtrusive method of binding an event to click.
You also said:
Using onclick = function() { return eval(js); } doesn't work because you are not allowed to use return in code passed to eval().
No - it won't, but onclick = eval("(function(){"+js+"})"); will wrap the 'js' variable in a function enclosure. onclick = new Function(js); works as well and is a little cleaner to read. (note the capital F) -- see documentation on Function() constructors
BTW, without JQuery this could also be done, but obviously it's pretty ugly as it only considers IE/non-IE:
if(isie)
tmpobject.setAttribute('onclick',(new Function(tmp.nextSibling.getAttributeNode('onclick').value)));
else
$(tmpobject).attr('onclick',tmp.nextSibling.attributes[0].value); //this even supposes index
Anyway, just so that people have an overall idea of what can be done, as I'm sure many have stumbled upon this annoyance.
One gotcha with Jquery is that the click function do not acknowledge the hand coded onclick from the html.
So, you pretty much have to choose. Set up all your handlers in the init function or all of them in html.
The click event in JQuery is the click function $("myelt").click (function ....).
just use jQuery bind method !jquery-selector!.bind('event', !fn!);
See here for more about events in jQuery
If you don't want to actually navigate to a new page you can also have your anchor somewhere on the page like this.
<a id="the_anchor" href="">
And then to assign your string of JavaScript to the the onclick of the anchor, put this somewhere else (i.e. the header, later in the body, whatever):
<script>
var js = "alert('I am your string of JavaScript');"; // js is your string of script
document.getElementById('the_anchor').href = 'javascript:' + js;
</script>
If you have all of this info on the server before sending out the page, then you could also simply place the JavaScript directly in the href attribute of the anchor like so:
Click me
Note that following gnarf's idea you can also do:
var js = "alert('B:' + this.id); return false;";<br/>
var newclick = eval("(function(){"+js+"});");<br/>
$("a").get(0).onclick = newclick;
That will set the onclick without triggering the event (had the same problem here and it took me some time to find out).
Came up with a quick and dirty fix to this. Just used <select onchange='this.options[this.selectedIndex].onclick();> <option onclick='alert("hello world")' ></option> </select>
Hope this helps

Categories

Resources