I want to call another function before body, but how?
The system shows me the error undefined function myx
I only can add code after body.
<script type="text/javascript">
jQuery(function($){
function myx() {
alert("omg");
};
});
</script>
</head>
<body>
<script>
jQuery(document).ready(function($){
$("mytest").click(function(){
myx();
});
});
</script>
Check
That function is out of scope. You need to define the function outside the jQuery callback.
<script type="text/javascript">
function myx() {
alert("omg");
};
</script>
</head>
<body>
<script>
jQuery(document).ready(function(){
$("#mytest").click(function(){
myx();
});
});
</script>
Check
Use external JavaScript, so it's cached into the Browser Memory, so when your Client visits again it will load faster. Then look at this:
// wrapper is same as $(document).ready() with no-conflict
jQuery(function($){
// should be defined once everything has loaded
function myx(){
// never use alert except to test
alert('OMG!');
}
// passing a function name like a var is the same as Anonymous function
$('#mytest').click(myx);
});
// Ignoring outer wrapper to save indenting - indent everything further
The important thing is that myx should be defined after everything has loaded.
You don't have to, but it's a best practice to use external JavaScript and put the <script> tags in the <head>, setting both <script type='text/javascript' src='yourUrl.js'></script> to be W3C Compliant. Additionally, technologically the document.body may not be available to some older Browsers if your <script> tags are defined in the <body>, as HTML must be defined before JavaScript is able to get it, which is why you use the Anonymous function inside of jQuery() (same as $(document).ready() or the JavaScript onload Event). Then you get the HTML with JavaScript because those Elements are available onload.
Related
I am new to javascript so I make this thread. I read some post. In this post is the function inside or outside of the document ready. If it is declare outside the document can I re-use / call it in another JScript?.
As my title what should be the contain inside of a document ready?.
$(document).ready is an event which fires up when document is ready.
Suppose you have placed your jQuery code in head section and trying to access a dom element (an anchor, an img etc), you will not be able to access it because html is interpreted from top to bottom and your html elements are not present when your jQuery code runs.
To overcome this problem, we place every jQuery/javascript code (which uses DOM) inside $(document).ready function which gets called when all the dom elements can be accessed.
If you place your jQuery code at the bottom (after all dom elements, just before ) , there is no need for $(document).ready
See the example, which alert calls first that will give you an idea what should be inside the ready.
alert("Without Ready");
$(document).ready(function(){
alert("With Ready");
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
.ready makes sure your DOM is ready and good to go for binding, so putting all your functions inside there like the events functions would only be bootstrap at ready state of the document. Normal functions( with name i.e non anonymous functions) can be declared outside the document.ready so you can re-use it somewhere else. since those functions are called from the document.ready events or jquery code to be used.
See more about document.ready here. check the snippet below for a brief example layouting
/**
Global function here, which is not called or bind on page load
*/
function alertWindow(message){
alert ("Window is loaded here with Message: "+message);
$("#console").text(message);
}
$(document).ready(function(){
$("#showBtn").click(function(event){
var ourMessage = $("#message").val();
alertWindow(ourMessage);
});
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<input type="text" id="message" placeholder="Enter Message" >
<br>
<button id="showBtn">Show Message</button>
<p>
<h3>Console Here</h3>
<div id="console"></div>
</p>
when we use document.ready all the listeners and all the functions inside the document ready will work only after the page load completed.
So for example if you added any listener to a button and that perform some change in your page then better to write it inside the document.ready.
First things first - In JavaScript a function defines the scope of the code it contains, so if you want to share it you need to define it in a location that your other code can see.
You also don't need to define functions inside the document ready function, you could just define outside of the ready() callback. Eg,
$(document).ready(function(){
$('button').click(function(){
somefunc();
});
});
function somefunc()
{
alert('yes');
}
$(document).ready(function(){
// do something else
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
Hope this help..
The ready event occurs when the DOM (document object model) has been loaded.
Because this event occurs after the document is ready, it is a good place to have all other jQuery events and functions. Like in the example above.
source : http://www.w3schools.com/jquery/event_ready.asp
For example: if DOM is not fully loaded and our JS code is trying to access unloaded DOM. We will get Javascript error. To avoid this we need to give some time for loading document. To achieve this, We have a callback function for DOM loaded $(document).ready() or $(function)
We can have functions out side ready and those we can access for other JS also. It is always better to write Jquery add event and other Jquery related code inside ready method.
Refers from here:
A page can't be manipulated safely until the document is "ready."
jQuery detects this state of readiness for you. Code included inside
$(document).ready() will only run once the page Document Object
Model (DOM) is ready for JavaScript code to execute. Code included
inside $(window ).load(function() { ... }) will run once the entire
page (images or iframes), not just the DOM, is ready.
Since usually we've used jQuery to selecting and/or manipulating the DOM, so the best way to that is after the DOM is fully loaded. For those reason, so we need an event to watch the DOM ready state. This method give us flexibility where we'll write our javascript code, either on <head> nor at the end of <body>.
See my snippet samples below:
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
// this will not work properly
$('div').html('Hello World!!!');
</script>
</head>
<body>
<div>Hi brother!!</div>
</body>
</html>
Above script will not work properly since the script was executed
before the DOM loaded properly. So, the jquery can not find the
element with div tag.
To make the script running smooth, we need to add additional event listener from jquery named $(document).ready() as you can see at snippet below.
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
// this will work properly
$(document).ready(function() {
$('div').html('Hello World!!!');
});
</script>
</head>
<body>
<div>Hi brother!!!</div>
</body>
</html>
But, how if we don't want to add ready method? We still can do that, if we write the script below required DOM, see below snippet for example:
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
</head>
<body>
<div></div>
<script>
// this will not work properly
$('div').html('Hello World!!!');
</script>
</body>
</html>
UPDATE :
Refers from OP comment below:
In your reference I read use the shorthand $() for $( document
).ready() so I can use like $() for document.ready?
YES, you can use that shorthand, see my snippet below:
<html>
<head>
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<script>
// this will work properly
$(function() {
$('div').html('Hello World!!!');
});
</script>
</head>
<body>
<div>Hi brother!!!</div>
</body>
</html>
I want to execute a function at the end when the HTML has been loaded. I tried it with onload without success. I also tried it with ready, but it still doesn’t work. Here is my code. This is again placed in the header:
<script type="text/javascript">
$(document).ready(function() {
$('#infowindow_content').html('test');
});
</script>
The div is also set by an external JavaScript file. Content:
window.onload = initialize;
function initialize() {
document.getElementById('infowindow_content').innerHTML = 'testa';
}
It is included the following way before the closing body tag:
<script type="text/javascript" src="../lib/functions.js"></script>
I tried to place the above code before the closing body tag, but currently I have no idea why this doesn't work (the content isn't changed by my JavaScript code). If I execute it on the console afterwards everything works fine.
Solution:
I set a configuration parameter (language) in the HTML file. In the JavaScript file I ask for this value and depending on the value I define another content. Sometimes it could be so simple ...
Try this:
setTimeout(function() {
$(document).ready(function() {
$('#infowindow_content').html('test');
});
}, 20);
I don't know the jQuery equivalent but try the native JS.
Since the <body> has the most HTML & loads after <head>...
document.body.onload=function(){
yourFunction(args)
}
<body onload="yourFunction(args)">...</body>
Or maybe the window object, since it's the root of every webpage DOM...
window.onload=function(){
yourFunction(args)
}
Always place DOM manipulating code directly before your </body> tag. JavaScript in the header should only be called to libraries, such as jQuery.
This is a common idiom:
<html>
<head>
<script>
(function($) {
$(document).ready(function(){
// some jQuery/JavaScript in here
}
})(jQuery);
</script>
</head>
....
So we using a JavaScript immediate function which executes some jQuery. Now usually, it is advised to put JavaScript down the end of the page to allow progressive rendering. My questions are:
If you are using JavaScript in the head, what difference does it make if you make the function execute immediately?
Will ${document).ready(...) block excution, or does it happen asynchronously?
It ensures that, inside the IIFE, $ === jQuery. Before this script excert, you could have other libraries included (such as Prototype), which have their own definitions of $.
<script src="/jquery.js"></script>
<script src="/Prototype.js"></script>
<script>
$(document).ready(function () { // error, $ is something to do with prototye
});
</script>
<script>
(function ($) {
$(document).ready(function () { // this works fine
});
}(jQuery));
</script>
It is not the execution of $(document).ready() that blocks execution, it's the downloading of remote scripts.
<script src="/jquery.js"></script> <!-- page is blocked whilst jQuery is downloaded -->
<script> // This doesn't block the page load
$(document).ready(function () {
});
</script>
Additionally, I wouldn't call that a common idiom. It's common when creating a plugin, but not for wrapping $(document).ready() in. The following was created for that, and has the same affect;
jQuery(document).ready(function ($) { // "jQuery is always passed as first param, alias with `$`
// Inside here, $ === jQuery
});
IIRC, it will be fired when the document is done loading and not prevent any other execution.
Two questions:
Does jQuery.load() run after the content of <script> is completely downloaded?
If in case, there is a <script> in the document that will inject another <script> dynamically, does load() run after after the content of the 2nd script is downloaded or it will run after the original, non-dynamic content is loaded?
Thanks
The example for the 2) question is like that:
<html>
<head>
<script src="myscrip1.js"></script>
<script>
$(document).load( myscript2.functionA );
</script>
</head>
</html>
Where myscript.js will inject myscript2.js into the dom.
in which myscript2.js include the function myscript2.functionA
Obviously, I want to run myscript2.functionA after myscript2.js is loaded completely.
:)
The document ready event is fired when all of the resources referenced in the initial HTML have been downloaded (or timed out in case there are errors). If you dynamically inject a reference to another script (like the facebook api, google analytics, etc) it's readiness is undefined with relation to the document ready event.
If you want to check that your external script is ready you can check that an object that it creates has been loaded.
<script type="text/javascript">
var startAfterJqueryLoaded = function(){
if(typeof jQuery === "undefined" ) {
setTimeout( startAfterJqueryLoaded, 100 );
return;
}
// jQuery is ready, do something
}
startAfterJqueryLoaded();
</script>
Or if you have control of the script you are dynamically injecting you can establish a global function that it will call when it's ready.
<script type="text/javascript">
window.dynamicScriptIsReady = function(){
// do something
}
</script>
// Dynamic.js
// ...Setup whatever
window.dynamicScriptIsReady();
If you put the load event handler within the standard document ready event handler wrapper, it will ensure that the external script is loaded first. You should consider this standard practice. The solution is simple:
<script src="myscrip1.js"></script>
<script>
$(document).ready(function() {
$(document).load( myscript2.functionA );
});
</script>
Consider a javascript file script.js which contains the code alert(theVar);
Now, i linked the js file to the document like
<script type="text/javascript">
var theVar= 'a alert';
</script>
<script type="text/javascript" src="script.js"></script> //Contains alert(theVar);
The variable theVar is used and i get a alert. This works fine.
When,
<script type="text/javascript" src="script.js"></script>
<script type="text/javascript">
var theVar= 'a alert';
</script>
is used, i am not getting a alert.
I know the problem is because of the variable, which is declared after loading the js file.
But is there any way to get the variable declared anywhere in the document ?
in script.js do
window.onload = function() { alert ( theVar ) }
Or your favorite library dom ready fn, so it invokes the callback after a certain event instead of immediately.
Though, this really depends on what kind of functionality script.js has, which you have not specified thus far.
The important bit is that code gets executed in the appropriate order. You should delay the call to alert(theVar) until the document gets fully loaded. For instance, you can attach an onload event handler to the window object.
It's also worth noting that calling external *.js files does not affect the way code gets run.
The simple solution:
Move the script.js inclusion to the last row of the body. That way a variable declared at any point in the document can be used.
The technical solution:
Inside script.js, hook on to the window.onload event before doing any evaluating. The result is the same as with the simpler solution, but allows you to keep you script tags in the head (or anywhere for that matter).