I have this test to load the Facebook JavaScript SDK synchronously:
<html>
<body>
<script>alert('1');</script>
<script src="https://connect.facebook.net/en_US/all.js" />
<script>alert('2');</script>
</body>
</html>
For me, the second alert is never shown, any ideas why?
Correction:
<html>
<body>
<script>alert('1');</script>
<script src="https://connect.facebook.net/en_US/all.js"></script>
<script>alert('2');</script>
</body>
</html>
More information: Why don't self-closing script tags work?
Related
I have two embedded scripts in my HTML files but only the first one runs. The second one doesn't execute, it's just supposed to change the text of the paragraph. I'm really not familiar with javascript and don't know if there's some async wizardry going on. If I remove the jquery include (and change the code to use the plain method of changing elements), it works fine.
<html>
<body>
<p id="next-track">
Next Track
</p>
</body>
<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js"/>
<script>
$("#next-track").html("Bye JavaScript!");
</script>
</html>
You have to separate the script tag, you cannot close it on the opening.
<html>
<body>
<p id="next-track">
Next Track
</p>
</body>
<script type="text/javascript" src="http://code.jquery.com/jquery-latest.min.js">
</script>
<script>
$("#next-track").html("Bye JavaScript!");
</script>
</html>
Hello my questions is about how a webpage is loaded! Here is my code:
<!DOCTYPE html>
<html>
<head>
<title>JavaScript</title>
</head>
<body>
<h1>Waiting</h1>
<script type="text/javascript">
alert("Why?");
</script>
</body>
</html>
I cannot for the life of me figure out why the alert is running before the heading is displayed. It is my understanding that since the alert is right above the closing body tag it will be the last thing run. Why is the page waiting for me to close out the alert before displaying the heading?
Thanks for the help!
Edit: I ran this code in firefox rather than chrome and it worked how I wanted it to - the heading displayed first before the alert ran.
You need to execute your script after the page loads with
<body onload="script();">
An external script will execute before the page loads.
<body onload="script();">
<h1>Waiting</h1>
<script type="text/javascript">
function script() {alert("Why?");}
</script>
</body>
You can use setTimeout() to show the alert after a few seconds (when the page should have loaded).
<!DOCTYPE html>
<html>
<head>
<title>JavaScript</title>
</head>
<body>
<h1>Waiting</h1>
<script type="text/javascript">
setTimeout(function(){
alert("Why?");
}, 1000);//wait 1000 milliseconds
</script>
</body>
</html>
You can check if the header (the h1 tag) is there and only alert if it is there.
<!DOCTYPE html>
<html>
<head>
<title>JavaScript</title>
</head>
<body>
<h1 id="header">Waiting</h1>
<script type="text/javascript">
var x;
x = setInterval(function(){
if(document.getElementById("header")){
alert("Why?");
clearInterval(x);
}
}, 100);
</script>
</body>
</html>
The simplest workaround code without using JQuery I could write is this. Please check it.
<!DOCTYPE html>
<html>
<head>
<title>JavaScript</title>
</head>
<body>
<h1>Waiting</h1>
<script type="text/javascript">
window.onload = function(){
setTimeout(()=>{
alert("Why?");
},10)
}
</script>
</body>
</html>
The cleanest way to do this seems like it would be to put your javascript in a separate file, and load it with the defer attribute. This will cause it to fire after the DOM loads (technically, just before DOMContentLoaded, but it doesn't work consistently across browsers unless there is a src attribute, which is why you would need to move it to an external file.
<script src="myScript.js" defer></script>
Oddly, adding some CSS to your heading could also affect this since JS is supposed to execute in order after any pending CSS.
The timeout function or a $(document).ready() function will do what you need in theory, but a timeout could need to be adjusted based on the complexity of the page, and if you aren't already using jQuery, you probably won't want to add it just to use $(document).ready().
I am learning javascript and i can't manage to make this work, an alert message should appear when i click the submit button
Html
<html>
<head>
<title>Understanding the Document Object Model</title>
<script type="javascript" src="script.js"></script>
</head>
<body>
<h1 id="title">Understanding the Document Object Model</h1>
<p id="first">This is the first paragraph</p>
<p id="second"><strong>This is the second paragraph</strong></p>
<p id="third">Third paragraph</p>
<input type="submit" id="clickMe" value="Click Me"/>
</body>
</html>
Javascript script.js
window.onload=function(){
document.getElementById("clickMe").onclick=runTheExample;
}
function runTheExample(){
alert("running the example");
}
Your type attribute is wrong.
It should be "text/javascript"
It works fine for me after making that change
==================================
EDIT:
As a note, my debugging process was to try invoking the alert() directly in the script. script.js became:
alert("running the example");
window.onload=function(){
document.getElementById("clickMe").onclick=runTheExample;
}
function runTheExample(){
alert("running the example");
}
That was triggering the alert either, which says that the whole script isn't in play. So it must be the invocation of the script that's the problem.
Once you've determined that, there aren't many things left to check.
<script type="text/javascript" src="script.js"></script>
You change your external javascript file link like this. Because,type attribute of script tag should come as text/javascript
I'm trying to use an external JavaScript file in order to write "Hello World" into a HTML page.
However for some reason it does not work, I tried the same function and commands inline and it worked, but not when it's using an external JavaScript file. The part I commented out in the JS file was the previous method I was trying to use. Those lines of could worked when I ran the script from the header, and inline. Thanks
Html file:
<html>
<head>
</head>
<body>
<p id="external">
<script type="text/javascript" src="hello.js">
externalFunction();
</script>
</p>
<script type="txt/javascript" src="hello.js"></script>
</body>
</html>
JavaScript file
function externalFunction()
{
var t2 = document.getElementById("external");
t2.innerHTML = "Hello World!!!"
/*document.getElementById("external").innerHTML =
"Hello World!!!";*/
}
In general, you want to place your JavaScript at the bottom of the page because it will normally reduce the display time of your page. You can find libraries imported in the header sometimes, but either way you need to declare your functions before you use them.
http://www.w3schools.com/js/js_whereto.asp
index.html
<!DOCTYPE html>
<html>
<head>
<!-- You could put this here and it would still work -->
<!-- But it is good practice to put it at the bottom -->
<!--<script src="hello.js"></script>-->
</head>
<body>
<p id="external">Hi</p>
<!-- This first -->
<script src="hello.js"></script>
<!-- Then you can call it -->
<script type="text/javascript">
externalFunction();
</script>
</body>
</html>
hello.js
function externalFunction() {
document.getElementById("external").innerHTML = "Hello World!!!";
}
Plunker here.
Hope this helps.
Script tags with SRC values do not run the contents. Split it to two script tags. One for the include, one for the function call. And make sure the include is before the call.
use onload eventListener to make it simple
<script>
window.onload = function() {
externalFunction();
}
</script>
You're trying to call the function before it has been loaded.
Place the load script above the declaration:
<html>
<head>
<script type="txt/javascript" src="hello.js"></script>
</head>
<body>
<p id="external">
<script type="text/javascript">
externalFunction();
</script>
</p>
</body>
</html>
Also you have a typo:
<script type="txt/javascript" src="hello.js"></script>
Should be:
<script type="text/javascript" src="hello.js"></script>
The script type needs to be "text/javascript" not "txt/javascript".
Should the following display "Test" in a message box? If not, what changes should I make?
<html>
<base href="http://www.google.com"></base>
<body>
<script language="JavaScript" type="text/javascript" src="test.js"></script>
</body>
</html>
test.js contains:
alert("Test");
Yes. See here I've inserted this into a jsFiddle example. Next time try to just do it instead of asking a question. You can see the example here
alert("Test");
is the command that does a msg box!