Why doesn't this work in a browser?
<input type="button" id="x">
Click
Yes, I know that I can use onClick to call a function and put my code there, but is there a way to use 'javascript:' with the href attribute to do simple javascript functions like changing a value?
Assignment "returns" the value assigned. Returning any kind of value from a javascript: link indicates to the browser that it should replace the document with that value.
Usually you might see javascript:void(stuff goes here) to suppress the return value.
You already seem to be aware of why you shouldn't do this, though. onClick event handler is a step in the right direction, but really it should be attached externally.
Yes, that should work and as you know onclick is another easy approach to do it;
However if you still want to it with href you may try this -
(this might look unwillingly big :)
<input type="button" id="x">
Click
Related
what is the difference between
<a onclick="someFunction">
and
<a onclick="someFunction()">
One uses the parenthesis and not the other, but what are the differences of using either? What is the "correct" option? And what happens if i dont use any href attribute?
As far as I know, in javascript, using something = someFunc(); assigns the return value of that function to the something variable. And using something = someFunc; assigns the function directly (not its result) to that variable (And it's mostly used to assign functions to events). e.g. I can assign a function to a onclick event.
But what I don't understand is what happens when using either in some html element inline event, as in the examples, since the assignation is not to a javascript variable, but to an html attribute, which happens to be an event? Please explain.
And also, is there a difference on assigning a inline onclick function to an anchor (a) that to other elements (e.g. span div label etc)? Do they have the same effect?
Sidenote:
I've been reading here about how to run a function when clicking on a link, and I already understood is that is should not be done "inline", but instead using unobtrusive javascript. (I mention it to avoid debate about that), but in the examples I've seen they don't mention the difference of both options I mention when doing it inline.
Edit: This question was made because here they gave an answer which doesn't use the parenthesis in the function for the event, and nobody mentioned the parenthesis were needed, so I assume it is valid. yet I don't know what is the difference of using () or not.
One uses the parenthesis and not the other, but what are the differences of using either?
<a onclick="someFunction"> won't do anything. The parenthesis cause a function to be called.
Having a statement consisting of nothing but an identifier (be it a function name, variable, or whatever) won't do anything (except throw a reference error if the variable doesn't exist).
And what happens if i dont use any href attribute?
Then I'd question why you were using an <a> element in the first place.
And also, is there a difference on assigning a inline onclick function to an anchor (a) that to other elements (e.g. span div label etc)?
Only that they aren't (by default) focusable elements (nor is an a element without an href attribute), so the click event couldn't be triggered by tabbing to the element and pressing enter. If you want an element that will do something with JS when triggered, and you don't have a sensible fallback for when JS isn't available, use a button.
The value of an event handler attribute is a sequence of Javascript statements, not an expression.
It isn't assigning a function value to the property; it's a piece of code to execute at that event.
Leaving out the parentheses, results in an expression statement that has no effect.
when writing inline on click functions, we assigning the code to be executed in the form of string on click of the element.
It is equivalent to eval('someFunction()');
we cannot write on click='someFunction' since it will be equivalent to eval('someFunction') which would do nothing.
if you intend to bind a click handler to an anchor tag, dont forget to add a href='#' attribute to the anchor tag.
There is no difference between assigning a click handler to span or divs as compared to anchor tag.
I have code like this
<a id="id101" href="javascript:func1();" onclick="return func2();">Link</a>
func2 returns true or false. Then, func1 is called only when function2 returns true. Right ?
In learning jquery, I found out that onclick is not good and depreciated, so I modified above code to
<a id="id101" href="javascript:func1();">Link</a>
jquery
$("#id101").click(func2() {
//same stuffs from before which was in func2
});
Now, my question is:
after click handler is taken care of, what can I do with JavaScript inside href? Should I call func1 inside func2 in jQuery click handler of func2, when condition inside func2 is true?
Or is there some elegant solution?
Also, Separating html and events code is good, but here this element with id id101can have many events associated with it, and in a large file, there might be so many html elements with many events. So, when I have a large page with many event handlers, then how can I better know which html element has which and how many events associated with it?
More explanation to above question as requested,
I meant id101 can have onclick, onmouseover, onmouseout and many other such events. There can be many such elements with many such event handlers. How do I better spot them ? In old style, all such event handlers are all placed together, like this
<a id="id101" href="javascript:func1();" onclick="return func2();">Link</a>.
I am not saying this is good, but atleast I can see that it has this onclick event. But now when separting this into jquery file, I have to search first this jquery file for id101 and then check events associated with it, which can be problem with html file having many elements and associated event handlers. Is there any better way to to find that information ?
If I understand correctly, you want to avoid the inline Javascript, but you also want to be able to glance at an a and know if it has an event bound to it. Unfortunately, there isn't an acceptable way to denote this, as inline Javascript is bad news. Perhaps you can just give your element a dummy class to aid your future readability. Other than that, forget the whole func1 and func2 thing. Just use an anonymous function inside of your click binding.
<a id="some_id" class="optional_has_click">Click Me</a>
<script type="text/javascript">
$(document).ready(function(){
$("#some_id").click(function(){
// do something
alert( $(this).attr("id") );
});
});
</script>
EDIT: Also, removing the href will remove the visual cue, so you can use your dummy class to make it look like an a.
Here is a fiddle for you: http://jsfiddle.net/zzTSt/1/
The best I can tell you is that this is "smelly" code--you don't want your javascript all over the place like this. I would recommend you spend a few more hours learning some jQuery fundamentals and move on from there. I know it can be frustrating, especially if you are working with legacy javascript.
Yes, I recommend you to write func1 inside func2.
HTML:
<a id="id101" href="#" >Link</a>
jQuery
$("#id101").click(func2() {
var status = false;
//func2 goes here and modifies status value.
if (status) {
// func1 goes here
} else {
// in case if status is false.
}
});
Also I didn't get what you mean in second part of your question, could you please be more specific.
i have an element in html as shown below.
<tr><td class="HELPTEXT"><span lang="HLPMTXT1" id="HLPMTXT1"></span></td></tr>
i want to change the value of lang according to particular condition.
I tried as given below.but its not working.
<script>
document.getElementById("HLPMTXT1").lang ="HLPMTXT2"
</script>
Could anyone help me for changing the value of lang attribute of span?
You should use setAttribute(name, value) to do that, so your code would look like:
document.getElementById("HLPMTXT1").setAttribute("lang", "HLPMTXT2");
You can also use getAttribute(name) to retrieve the value using JavaScript.
https://developer.mozilla.org/en/DOM/element.setAttribute
https://developer.mozilla.org/en/DOM/element.getAttribute
Edit: It's also possible that your script is not working because you're trying to access the element before it exists in the DOM. Best way to insure that your element exists is by either: a) putting your script tag after the element, b) using the unload event to delay execution of your JS until everything is loaded, or c) use the DOMContentLoaded event. The latter, however, is a bit tricky to get to work cross-browser (without reusing somebody else's code that already addresses those problems) so you might want to read up on it first.
document.getElementById('HLPMTXT1').setAttribute('lang', 'HLPMTXT2');
Not all attributes can be accessed through the object properties
For example i'm using append, and for example i'm appendig button in to a div, and i have function $('button_id').click(... etc to work affter i append the div, how can i do that.I mean i get no errors, but the function is not starting, it's because i append and then i want to use the function but how to do that, i tryed with delegate, but same thing.I tryed with function in the button tag , onmouseover and then the function thing, but nothing it gives me function not found.What is the solution ?
I have two events, one event is click event that appends button, the other event is click event that does something if the button that was appended is clicked, but that second event is not working ?
Try using :
$(elem).live(...)
It will bind event for now and in the future.
Firstly, it always helps if you show us the exact source code. $('button_id') is the incorrect selector to start with, try something more along the lines of $('#button_id') as your selector. Also, are you appending dynamic content? Anyways, I've always used the delegate() function quite successfully, but have you tried using the live() function? Also, one more thing to make sure of is that you have the newest version of jQuery as your source.
As was stated as well, you can not have duplicate ids, if you want to have a pointer, use class, instead of id="some_id" use class="appended". To select those using jQuery, use the selector like this $('.appended').
Try something like this it will work as per your expectations.
$("#button_id").click(function(){
//On click code goes here
}).appendTo($("#div_id"));
It's difficult to determine the problem you're having without seeing your code, but delegate (or live) should be perfect for what you're trying to do:
$("body").delegate("#b", "click", function() {
alert("ok");
});
$("#example").append('<input type="button" id="b" value="Click" />');
The click handler above will fire when an element with id="b" is clicked, whether or not that element happens to be in the DOM right now or not.
However, as others have noted, it's important to remember that IDs need to be unique within a document, so by the sounds of it you may be better of using classes instead.
You can see an example of the above code running here.
If I have a some javascript in an anchor's href attribute:
<a href="javascript:alert('hello!')">
Is there a way I can get a reference to the DOM element that was clicked when the script executes? I mean, I know I could do
<a href="javascript:alert('hello from '+document.getElementById('thisAnchor'))" id="thisAnchor">
But I was hoping for something more like
<a href="javascript:alert('hello from '+target)">
Something like this?
Example: http://jsfiddle.net/TTzDb/
me
Using onclick, this will refer to the element that received the event.
Move the JavaScript to the onclick="yourJavaScriptHere" attribute. Then you can use the 'this' keyword to reference your anchor. So
some text
Although, that isn't very meaning. Additionally, it is a better practice to separate your JavaScript from your HTML to build a more maintainable website.
Yes, and the answer is this which refers to current DOM element:
Click me
EDIT:
Of course as bobince mentioned (see comments) that won't work as excepted. The correct form is:
Click me