I am including an external JS file, which has some code that I need to run after a particular thing happens (after contact form is submitted).
The external file has a function but also calls the function. This isn't much of a pain if it was OK to run that function on page load, but I need to run its function after a form is submitted. My form is submitted via AJAX, so I need to run the external file's function after the form has submitted, only.
How can I do this?
Here's an illustration to help...
MY SITE'S FOOTER:
<script type="text/javascript">
var a_variable = 12345;
</script>
<script src="//domain.com/external.js" type="text/javascript"></script>
</body>
</html>
CONTENTS OF EXTERNAL.JS:
function doThis(){
alert(window.a_variable);
}
doThis();
But I only want to run doThis() at a time that I want, not on page load.
Can I stop doThis(); from executing until I explicitly tell it to?
NOTE: I have already tried including external.js by creating a script tag (in javascript) and loading it that way, but the function in external.js needs to write to my users' browser, to which the users' browser says Failed to execute 'write' on 'Document': It isn't possible to write into a document from an asynchronously-loaded external script unless it is explicitly opened.. After that, I looked into the solutions in this answer, but it did not solve the problem. So, I am looking for a way to stop doThis() from executing.
Can you edit the external.js file? If so you should just remove the doThis() line and add a listener to call the function on window load like so:
function doThis(){
alert(window.a_variable);
}
window.onload = doThis;
If you cannot edit the JavaScript file you are a bit stuck. You could try to rewrite it and just include it locally, following the above pattern (since you can pull the file I assume you have access to the source and could easily download the file and edit it). I would suggest this course of action.
If you really need it to be pulled from that specific source and cannot edit the file, you can look into something like require.js. This will allow you to load a JavaScript file from within other JavaScript code, so you can wait for the document to load before including it. So your html could be:
<html>
<body>
<script type="text/javascript">
var a_variable = 12345;
window.onload = function() {
require(["//domain.com/external.js"], function() {
console.log("loaded!");
});
}
</script>
<script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/require.js/2.3.3/require.js"></script>
</body>
</html>
Related
I am trying to get a script from another website using jQuery then document.write it
here is my code
var url = "https://code.jquery.com/jquery-1.10.2.js";
var dam = $.getScript(url);
document.write(dam);
But this doesn't work!!
all what I get on the page is [object Object]
Can this be achieved without XHR?
jsfiddle
Don't use document.write, it does not do what you think it does. What it does not do is write some data at the end of the document. What it does instead, is pipe data into the current write stream. And if there is no write stream, it will make a new one, resetting the document's content. So calling document.write(dam) means you just wiped your document. document.write is a low level JS function from an earlier era of JavaScript, don't use it.
Instead, you want to use modern DOM manipulation functions, so in jQuery, that's stuff like:
$(document.head).append($("<script>").attr("src", url));
where
$("<script>")
builds a new script element,
$(...).attr("src", url)
sets the "src" attribute to what you need it to be, and:
$(document.head).append(...)
or
$(document.body).append(...)
to get the script loaded into your document. If it's a plain script with src attribute, it can basically go anywhere, and if it's a script with text content that should run, you can only make that happen through document.head.
Although if it's just a script you need to load in and run, you can use getScript, but then you don't need to do anything else, it's just:
var url = "https://code.jquery.com/jquery-1.10.2.js";
jQuery.getScript(url);
Done, jQuery will load the script and execute it. Nothing gets returned.
Of course, the code you're showing is loading jQuery, using jQuery, so that's kind of super-odd. If you just want to load jQuery on your page, obviously you just use HTML:
<!doctype html>
<html>
<head>
...
</head>
<body>
...
<script src="http://https://code.jquery.com/jquery-1.10.2.js"></script>
</body>
</html>
with the script load at the end so the script load doesn't block your page. And then finally: why on earth are we loading jQuery version 1.x instead of 2.x? (if you need to support IE8: that's not even supported by Microsoft anymore, so you probably don't need to).
And finally, if we don't want to load the script, but we really just want its content, as plain text, there's only a million answers on Stackoverflow already that tell you how to do that. With jQuery, that's:
$.get("http://https://code.jquery.com/jquery-1.10.2.js", function(data) {
$(document.body).append($("div").text(data));
});
But you knew that already because that's been asked countless times on Stackoverflow and you remembered to search the site as per the how to ask instructions before asking your question, right?
executing the script on the page is not my goal!. I want to get the
script content and put it a div (USING JAVASCRIPT - NO XHR) , is that
possible ?
Try utilizing an <iframe> element
<div>
<iframe width="500" height="250" src="https://code.jquery.com/jquery-1.10.2.js">
</iframe>
</div>
jsfiddle http://jsfiddle.net/snygv469/3/
Make it easier... use my fiddle
http://jsfiddle.net/wwwfzya7/1/
I used javascript to create an HTML element
var url = "https://code.jquery.com/jquery-1.10.2.js";
var script = document.createElement("SCRIPT"); //creates: <script></script>
script.src = url; //creates: <script src="long_jquery_url.js"></script>
document.body.appendChild(script); //adds the javascript-object/html-element to the page.!!!
Use this way, it can fix your problems.
$.get( "https://code.jquery.com/jquery-1.10.2.js", function( data ) {
alert(data);
});
You can try adding
<script src="http://code.jquery.com/jquery-1.8.3.min.js" ></script>
Then an AJAX call, but it pulls data from CACHE. It looks like an AJAX but when <script> is added file goes in cache, then read from cache in the ajax. In cases where it is not stored in cache read it using normal AJAX.
jQuery.cachedScript = function(url, options) {
// Allow user to set any option except for dataType, cache, and url
options = $.extend(options || {}, {
dataType: "text",
cache: true,
url: url
});
// Use $.ajax() since it is more flexible than $.getScript
// Return the jqXHR object so we can chain callbacks
return jQuery.ajax(options);
};
$(document).on('ready', function() {
// Usage
$.cachedScript("http://code.jquery.com/jquery-1.8.3.min.js").done(function(script, textStatus) {
console.log(script);
});
});
Normal Solution
If you are ready to use AJAX look at this fiddle
How to fetch content of remote file and paste it on your document and execute that js code
I guess you want to get content written on remote file and want to write that content in your HTML. to do this you can use load() function.
To do this follow the following steps:
1. Create a file index.html Write the following code in it:
<pre id="remote_script"></pre>
<script>
$(document).ready(function() {
//var url = "https://code.jquery.com/jquery-1.10.2.js";
var url = "remote_script.html";/* For testing*/
$('#remote_script').load(url,function(){
eval($('#remote_script').text()); /* to execute the code pasted in #remote_script*/
});
});
</script>
2. Create another file remote_script.html for testing write alert('a'); in it without any <script> tag and run the above code.
I have trouble to call external javascript function.
In my HTML:
<p> <a id="delete" href="/some/url/">Delete</a> </p>
I want to confirm before deletion. If I put the code in the html file, it works:
<script>
var test = document.getElementById("delete");
test.onclick = function popup(){return confirm("Are you sure?")};
</script>
However, if I put popup() function in external js file and include using "src=/path/to/external.js", the function cannot find, and no pop up window anymore.
I am pretty sure I type the correct path of external js, because I can open the js file in the html page source code. Also, if I use jquery.js file locally, it will not work, but if I use the jquery.js served by google CDN, it works. I am totally lost. Why this happens?
You need to be sure that when your JS is executed, the #delete element does exist in DOM.
To do so, you could simply include the .js file before </body>.
If you'd like to include it before </head>, your should fire the event binding after DOM ready (on DOMContentLoaded event, or later, window.onload), because JS is executed once it's downloaded, and at that time <body> is not rendered yet, document.getElementById("delete") would be null.
If you want to separate the event listener, you could try following code:
function popup(){return confirm("Are you sure?")}
test.onclick = popup; // Attention! Without brackets here.
Because the HTML element may not be on the page when the code is executed.
Use below:
window.onload=function(){
var test = document.getElementById("delete");
test.onclick = function popup(){return confirm("Are you sure?")};
};
This is a bit of an oddball use case, but I have my reasons:
I'd like to be able to write
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
in my markup and, using the code in first.js, prevent or delay the execution of second.js. Is this possible, in any browser? What if the contents of first.js are inlined? (If it helps, assume that the second script tag has an id attribute.)
Since I've gotten a couple of answers that missed what I'm getting at, I should clarify:
The solution must be entirely within first.js. Anything that require changes to the original HTML of the page, or to second.js, is not acceptable.
It is acceptable to load second.js via Ajax and execute it using eval. That's the easy part. The hard part is preventing the immediate execution of second.js.
Assume that you don't know what's in second.js. So, you can't just replace each global function called by second.js with a no-op function. (Plus, this would almost certainly lead to errors.)
If you know of a solution that works in some browsers but not in others, I'd love to hear it.
Example: To make this a little more concrete, let's say that the code
<script type="text/javascript">
function func() {
window.meaningOfLife = 42;
window.loadSecond();
};
setTimeout(func, 10);
</script>
precedes the two script includes, and that second.js contains the line
if (window.meaningOfLife !== 42) {throw new Error();}
first.js should be able to prevent this error by delaying second.js from executing until window.loadSecond is run. (Assume the implementation of window.loadSecond is also in first.js.) It is not allowed to touch window.meaningOfLife.
Update: Alohci's answer meets these requirements, but only on the condition that the second script tag comes immediately after the first, with nothing but whitespace in between. If someone could extend his hack to avoid that requirement, without introducing other unwanted consequences, that would be amazing...
Given your specific requirements set, this is actually quite simple and should work completely cross-browser. It does require however, that first.js immediately precedes second.js without anything between them except white space.
First, let's assume that the HTML looks like this:
<!DOCTYPE html>
<html>
<head>
<title>Test Case</title>
<meta charset="UTF-8" />
<script type="text/javascript">
function func() {
window.meaningOfLife = 42;
window.loadSecond();
};
</script>
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
</head>
<body>
<p>Lorem ipsum dolor sit amet ...</p>
Run Func()
</body>
</html>
I've removed the setTimeout because that can cause func() to run before start.js runs causing a "loadSecond is not defined" error. Instead, I've provided an anchor to be clicked on to run func().
Second, let's assume that second.js looks like this:
document.body.appendChild(document.createTextNode("second.js has run. "));
if (window.meaningOfLife !== 42) {throw new Error();}
Here, I've just added a line to append some text to the document body, so that it is easier to see when second.js actually runs.
Then the solution for first.js is this:
function loadSecond()
{
var runSecond = document.createElement("script");
runSecond.setAttribute("src", "second.js");
document.body.appendChild(runSecond);
}
document.write("<script type='application/x-suppress'>");
The loadSecond function is just there to run second.js when func() runs.
The key to the solution is the document.write line. It will inject into the HTML <script type='application/x-suppress'> between the close script tag of first.js and the open script tag of second.js.
The parser will see this and start a new script element. Because the type attribute has a value which is not one that the browser recognises as being JavaScript, it will not attempt to run its content. (So there are an infinite number of possible type attribute values you could use here, but you must include a type attribute, as in its absence, the browser will assume that the script's content is JavaScript.)
The second.js script's opening tag will then be parsed as text content of the new script element and not executed. Finally the second.js script's closing tag will be re-purposed to close the new script element instead, which means that the remainder of the HTML is parsed correctly.
You can see a working version at http://www.alohci.net/static/jsprevent/jsprevent.htm
In first.js, set var shouldILoad = true
Then, load second.js this way:
<script>
if (shouldILoad) {
(function() {
var myscript = document.createElement('script');
myscript.type = 'text/javascript';
myscript.src = ('second.js');
var s = document.getElementById('myscript');
s.parentNode.insertBefore(myscript, s);
})();
}
</script>
(where 'myscript' is the ID of some element before which you'd like to insert the new Script element)
As far as I know, you can't. If the markup looks like
<script type="text/javascript" src="first.js"></script>
<script type="text/javascript" src="second.js"></script>
you can't access the second script element from within first.js, as it hasn't been added to the DOM at the moment the first script runs (even not if you assign an id to the second element). It doesn't matter whether the code of second.js is put inline or in an external file.
The only thing I don't understand is your second point. First you say that you can't control the markup of the document, but then you state it is possible to load second.js dynamically (using AJAX).
Following article describes the way you could block (3-rd party) scripts loading/execution from your script (including the both tag in the page head and dynamically added tags).
To handle existing tags on a page:
Use a MutationObserver to observe script elements insertion and inside the MutationObserver callback backup the script (to enable/insert it later) and change the script type to "javascript/blocked" (not works in IE, Edge, Firefox). Also you could handle deprecated (but working) beforescriptexecute event in Firefox to prevent script load.
Manually set type "javascript/blocked" (works everywhere including IE and Edge) like
<script type="text/javascript" type="javascript/blocked" src="second.js"></script>, then backup it in MutationObserver callback and re-add it later.
To handle dynamically added tags
Monkey-patch the document.createElement.
Override ‘src’ and ‘type’ descriptors on the HTMLScriptElement prototype.
Also this guys provide a yett library with the approach described in the article.
All <script> tags have their own execution context, which makes it nearly impossible to interfere with each other. Of course you've got the (infamous) global object (referenced by window in browsers).
Preventing the execution of second.js is rather simple: break it!
Assuming that second.js tries to call document.getElementById for example:
Working example of breaking jQuery, then loading later (with dependecies).
Tested on: IE 6+, FF 3.6+, Chrome
end of first.js
var execute;
// saving our position
var scripts = document.getElementsByTagName("script");
var i = scripts.length;
// breaking getElementById
var byId = document.getElementById;
document.getElementById = null;
var interval = setInterval(function () {
if (i != scripts.length) {
var second = scripts[i];
// stop polling
clearInterval(interval);
// fix getElementById
document.getElementById = byId;
// set the delayed callback
execute = function (onload) {
var script = document.createElement("script");
script.src = second.src;
script.onload = script.onreadystatechange = onload;
document.getElementsByTagName("head")[0].appendChild(script);
};
}
}, 100);
anytime you wanna execute second.js
execute(function(){
// second.js dependant code goes here...
});
Note: the onload parameter for execute is optional.
Just to see if this was possible, I had first.js send a synchronous XHR to a PHP file, and had the PHP file delete second.js. When the readyState reached '4', I had the JS alert something, to stop the thread. Then I went and checked the server... Yeah, second.js was deleted. And yet, it wouldn't work. I'd close the alert box, and the code that was in second.js would still be executed, despite the fact that the file was gone.
I don't really know what this means, but the answer to your question is probably, "No, it's not possible."
you may use setTimeout() to delay the execution of some code
I want to ask a question about the Javascript’s onload.
I’m writing a JSP page with the code <%# include file ="body.jsp". The included body.jsp contains:
<table onload="function()">
This should load the javascript function, but it doesn't appear to have any effect on the page. Is onload only usable on the body tag?
Onload can only be used for <body>, <img>, <script>, <iframe> tags, because it tells you when an external resource (image, script, frame) or the whole page (body) has been loaded
Since HTML5 these can also fire a load event: <link>, <style>, <input type=image>, <object>
Support for these can still be a hit or miss though (e.g. older Android browsers)
Why not just include it via a <script tag>?
Inside your .jsp file
<script>
window.onload = function() {
alert("Hello!");
}
// or to execute some function
window.onload = myFunction; //notice no parenthesis
</script>
As the other guys already stated the onLoad event will not fire on a table. What you can do ist attaching the onLoad-handler to the body element (which will then fire, when the page is loaded) and manipulate the table by for example assigning an id to the table.
<body onload="function() { var table = document.getElementById("table-id"); ... }">
<table id="table-id"></table>
</body>
Are you using some javascript framework?
"onLoad" may be used on body- and frameset-tags.
To see some action you may use:
<body onload="function(){alert('This is an action!')}">
The easiest way i find is to use an external javascript file and jquery.
// Variables and functions you want to declare
var socket = io.connect();
// .....
// Function you want to run on load
$(function() {
$('#submit').click(function() {addUser();});
// ... any other functions you want to run on load
});
This is a code snippet from something that i was working on. The variable is declared before the code runs (It creates a web socket).
Then there is the jquery document selector ($) which runs on load and calls the init function to modify my html. I use it to call an anonymous function which runs right away.
You can throw a <script> tag right after your table with code. Once it gets to the script tag it would mean that the DOM for the table element above it has been loaded and can now be accessed in your script below it.
Note: The following below isn't applicable to the question but rather the other answers being given.
I recommend using the addEventListener function in javascript for adding the event. This makes sure that you are not overwriting or going to be overwritten by anyone else wanting to listen to the event.
Example
var iframe = document.getElementsByTagName('iframe')[0];
iframe.addEventListener('load', function(event){ console.log("iframe Loaded", event); })
I am using JQuery to inject dynamically script tags in the body tab of a webpage. I got something like :
function addJS(url) {
$("body").append('<script type="text/javascript" src='+url+'></script>');
}
I add several scripts this way, and try to use them right after. E.G :
lib.js
function core() {...}
alert("I'am here !");
init.js
addJS("lib.js");
c = new core();
test.html
<html>
<head>
<title>test</title>
<script type="text/javascript" src="init.js"></script>
</head>
<body>
Hello
</body>
</html>
Loading test.html pops up "I'm here" and then ends up with an error "core is not defined". Of course merging both of the JS files will make them work perfectly.
I just don't get it o_O.
EDIT
I simplified this example, but Jeff answer made me understand that it was a mistake. So here are some details :
init.js is not in the head of test.html when it reload because I inject it with a code exectuted on a bookmarklet.
So the real execution process is the following :
reload test.html > run the bookmarklet > jquery and init.js are inserted > lib.js is inserted
Sorry for the confusion.
EDIT 2
Now I have the solution to my problem (that was quick :-)) but I am still interested to the answer to my question. Why does this go wrong ?
jQuery has this functionality built in with getScript.
You get the "core is not defined" error because the scripts are loaded asynchronous. Which means that your browser will start loading lib.js in the background, and continue executing init.js, and then encounter "new core()" before the lib.js has finished loading.
The getScript function has a callback that will be triggered after the script is finished loading:
$.getScript('lib.js', function() {
var c = new core();
});
Notice your addJS function is appending to the end of the body element.
Since browsers will run scripts as they appear in the HTML source,
c = new core()
will run before your lib.js script is loaded (at the end of the body element).
I would recommend moving c = new core(); into the $(document).ready(function() {...}); or into a script element AFTER the body tag.
IMO, appending the script tag to the end of the document to load a script is rather unsightly. Reason:
you are trusting the browser to automatically fetch the script and load it.
You have no way of finding out whether the script is loading, has loaded, or if it encountered an error (maybe 404?)
The appropriate way would be to either use $.getScript(), or for a finer-grained control, fetch the script file with $.ajax() and use eval().
However, the second method has some issues: if you invoked eval() inside a function, then the script won't be available outside it! This mandates workarounds...
but why bother! use $.getScript() and get over with it :)
cheers, jrh.
In response to why your code is failing: Adding a script tag to the body does not block further script execution. Your code adds it, which starts the browser download process. Meanwhile, your script tries to call core(), which doesn't exist because lib.js hasn't finished downloading. jQuery works because it waits till the script finishes downloading before executing your callback function.