Functions come up as undefined if I place them in the document.ready() function:
$(document).ready(function(){
function foo()
{
alert('Bar');
}
});
foo(); // Undefined
Why does this happen? I'm sure I'm just in need of some simple understanding :)
Not sure why defining the function with in the scope of ready() is important to you, but you can make it work by declaring foo up front:
<html><head>
<script type="text/javascript" src="http://ajax.googleapis.com/ajax/libs/jquery/1.3.1/jquery.min.js"></script>
<script>
var foo; // Here's the difference
$(document).ready(function(){
foo = function ()
{
alert('Bar');
}
});
</script></head><body>
<input type="button" onclick="foo()" value="Click me">
</body></html>
Obviously you can't call foo() from the inline script immediately after ready() because the ready() code hasn't yet run, but you can call the function later on.
Just make sure that nothing can try to call foo() before the ready() code has run (or make the initial declaration of foo() a harmless function).
You can but they must be called within the scope of the ready() method otherwise they lose scope when the ready() method exits.
For example, the code below will work:
$(document).ready(function(){
function foo()
{
alert('Bar');
}
foo(); // still in the scope of the ready method
});
They will come up as undefined if you put them in any scope that is not theirs. If you really want to use them outside of the scope of $(document).ready(...) then you need to declare them externally. Such as:
var foo;
$(document).ready(function(){
foo = function()
{
alert('Bar');
}
});
foo(); // works now because it is in scope
Hope this helps.
Your function is defined within the scope of the $(document).ready() callback and cannot be seen from the outside. Either define the function outside the $(document).ready() scope of call it only from within.
Just another addition:
When declaring functions or variables inside of the $(document).ready() function, these are inaccessible when using onclick() binds in the document.
You can either move your declarations outside of $(document).ready(), or you can use $('#element').on('click', function() {}) within `$(document).ready().
<script>
$(document).ready(function(){
myfnc = function (param1, param2)
{
alert('Hello');
}
myfnc();
});
</script>
<input type="button" onclick="myfnc('arg1', 'arg2')" value="Click me">
Related
In my document I have an onLoad function given like here in this example:
<body onLoad="display()">
In addition I added a function at the end of the document which changes some CSS properties:
<script>
window.onload = foo(), bar();
</script>
Somehow the whole thing doesn't work! I tried to add all functions at the end of the document but I don't get it, somehow they don't trigger!
That will invoke the functions, but it doesn't assign anything useful to window.onload unless your last function happens to return a function.
You need to assign a function to window.onload that will invoke your functions when the window is ready.
window.onload = function() {
foo();
bar();
};
Plus, since you're putting the script at the bottom, you probably don't need the window.onload.
<script>
foo(); bar();
</script>
</body>
You should also be aware that assigning directly to window.onload will overwrite the script assigned in the <body onLoad=...>, so you shouldn't do both. Currently, the return value of bar(); is wiping out the function that invokes display();.
Getting rid of the window.onload assignment will fix that.
In the first case, I don't see a reason why it shouldn't work, as long as display() is defined function with no errors.
In the second case, when assigning event handlers via DOM, you need to pass either a function reference (i.e. instead of foo() just foo) or wrap it in an anonymous function like so:
window.onload = function() {
foo();
}
*Is there a way to call a function defined inside another function in javaSCRIPT? For example:
window.onload() = function() {
function my_function(){
print("Blah");
};
};
function function_two(){
my_function();
};
Is there a way to do something like the above (calling my_function in function_two even though it's defined inside the window.onload() function)? In my actual code, which also uses the raphael.js library, I'm trying to write a button in HTML, which using the onClick function, calls a function(like function_two) that runs the function defined in window.onload() (like my_function). However the console says that the my_function is undefined.
The scope of the function is the core issue here, as Zeychin and Trevor have said. I thought I'd offer another way of handling it. Basically, you can set your function to a variable that's in a higher scope (that is, accessible to both the onload and function_two functions), while defining it inside the onload function as you originally have:
var myFunction; //This is the placeholder which sets the scope
window.onload() = function() {
myFunction = function() { //Assign the function to the myFunction variable
print('blah');
}
}
function function_two() {
myFunction();
}
This might be handy if you only know the information you need for myFunction once you're in the onload event.
You can not do what you are asking to do.
The function my_function()'s scope is only within the anonymous function, function(). It falls out of scope when the method is not executing, so this is not possible.
Trevor's answer is the way to do this.
window.onload = function() {
my_function()
};
function my_function(){
alert("Blah");
};
function function_two(){
my_function();
};
Sorry for asking, but how do I access myFunction() from someFunction()?
<script>
$(document).ready(function() {
// Get messages
var myFunction = function() {
// doSth.
}
// Make the initial call on page load.
myFunction();
);
function someFunction() {
// Call the function a second time
myFunction(); // Call fails!
}
</script>
You are scoping it to the anonymous function you are passing to the ready method. Just move the definition outside that function.
Its more then a scope issue. Yes, you are scoping it to the anonymous function but even if you make it global by removing the var like this:
$(document).ready(function() {
// gets defined AFTER THE DOM IS READY
myFunction = function() {
// doSth.
}
}
// is called BEFORE THE DOM IS READY
myFunction();
It STILL won't work, because myFunction hasn't been defined by the time you call someFunction. someFunction is running immediately before the document is ready, which is BEFORE myFunction is defined.
Both functions need to be either in the document ready block, or outside it. If you need to manipulate DOM elements, I'd recommend inside.
If someFunction is called for a handler, you can remove the var declaration from myFunction and it will work as expected, because this will put myFunction in the global scope.
I don't think this will work because till the dom becomes ready and the document 'ready' event is fired the 'myFunction' function will not be created. The second call to 'myFunction' happens much before the 'myFunction' is created. This case will fail even if you create the function 'myFunction' in global namespace.
If you are not using any closure values inside your 'myFunction', you can move this function to global namespace. This will solve your ploblem.
Ex:
var myFunction = function(){
//Do somthing
}
$(document).ready(function(){
myFunction();
});
myFunction()
I think you wont be able to call myfunction() with your current code. You will have to get that function() { var myfunction = ... }; out of document.ready(). Seperate the method, then you can call myFunction.
myfunc() runs successfully when called from within the same js file. but it is undefined (Firebug) when called from an HTML page:
JS file:
$(function() {
myfunc() {
alert('inside myfunc');
}
alert('outside myfunc');
myfunc(); //this successfully runs myfunc()
});
HTML:
<script>
$(function() {
myfunc(); //this doesn't run myfunc(). It's undefined
});
</script>
But when I change myfunc() declaration to:
myfunc = function () { ... }
It's no longer undefined, and runs successfully.
Sorry for this very noob question, but what just happened? Why did it work when I changed the way I declared the function?
It's a matter of scope.
In
$(function() {
myfunc() {
alert('inside myfunc');
}
alert('outside myfunc');
myfunc(); //this successfully runs myfunc()
});
it is only available inside the anonymous function (function() { }), so it would also be unavailable if you were to call it outside of the anonymous function but inside the same js file.
While if you declare it using
myfunc = function () { ... }
myfunc is a global variable and the function is available everywhere.
In the first snippet, myfunc only exists with in the scope of the anonymous function you've defined. In the second snippet, myfunc is not within any visible scope. Finally, in the third snippet when you define myfunc at the top level, it's available at the global scope so any other part of your javascript will be able to call it successfully.
If you find yourself still having trouble understanding variable scope in Javascript, you might want to try reading through some of the results for "javascript scope" on Google for a more thorough explanation.
How can I call the Jquery Function From other javaScript Function (Not
from jquery function)
i.e
I have written some Jquery code like below
$(document).ready(function()
{
function func1(){
// Do Something.
}
});
Now I want to call the func1() function from other JavaScript Function
i.e Say an Example
function callJqueryFunction(){
**func1();**
}
The above javaScript function calling not work
but If do the same code inside a
$(document).ready(function()
{
function func1(){
// Do Something.
}
**func1();**
});
Its Work fine.
So what can I do for call the function which is inside a Jquery code
format.
this has nothing to do with jquery in general, it's just a scoping issue
function foo()
{
function bar() {
....
}
bar() // Ok
}
bar() // Not OK
function 'bar' is "local" in foo and is not visible outside of it.
if you want a function to be used in different contexts, declare it globally.
Isn't func1 scoped inside that ready function? If you declare func1 outside of ready it should be available to other javascript code just as any other function.
So:
$(document).ready(function()
{
func1();
});
function func1()
{
// Do something
}
function SomeOtherJavascriptFunction()
{
func1();
}
The function func1 is defined in the scope of the parent function. If you don't need this, you can simply move the definition outside (I expect in case of $(document).ready you don't really need it). Otherwise you will need to pass/store the function reference somewhere, and use that to call it.
You can do something like this
var funcToCall;
$(document).ready(function()
{
funcToCall = function func1(){
// Do Something.
}
});
funcToCall();