How do I pop up an alert in JavaScript? - javascript

How do I pop up an alert in JavaScript?
I tried alert"HELLO" but that didn't work.
Can someone tell me the correct syntax?

You need to add parentheses:
alert("HELLO");

Unlike VBScript, JavaScript requires parentheses around function calls.
Therefore, you need to write alert("Hello!");
It's also preferable (but not required) to end every statement with a semicolon ;.
Finally, if you aren't already, you need to put it in a script block, like this:
<script type="text/javascript">
alert("Hello!");
</script>
You can put JavaScript inside a script tag in an HTML page, or you can make a standalone .js file and double-click on it (in Windows) to run it using WSH.

<script type="text/javascript" >
alert("hello");
</script>

if you're having problems with alerts, it probably means your javascript is disabled in your browser, but if it isn't these methods should solve your issue.
<script type="text/javascript" >
window.alert("Hello World!");
alert("Hello World!");
</script>

Just add parantheses
alert("Hello");

<script type="text/javascript">alert("Hello");</script>

There are a few ways.
Use your web browser, type this code in address bar.
javascript:alert("Hello World!")
Open web developer in your web browser, go to console and type:
alert("Hello World!")
Type the code in .html or .js code as shown in other answers above.

Just add parentheses and enclosed it within the script tag.
<script type="text/javascript" >
alert("hello");
</script>

<html>
<head>
<script type="text/javascript">
function myFunction(){
alert("hello");
}
</script>
</head>
<body>
<input type="submit" onClick="myFunction()">
</body>
</html>
Here is the JavaScript function which has an alert box. This function is called by clicking on the submit button.

Related

Function didn`t render_template Flask [duplicate]

I have an HTML page with a typical structure:
<html>
<head>
<script src="..." ></script>
<style>...</style>
</head>
<body>
content
</body>
<script>
var success_callback = function(data) {
// REPLACE PAGE CONTENT & STRUCTURE WITH "data"
}
ajax(url, params, success_callback);
</script>
</html>
Do you think it is possible ? I've already tried to give the html tag an id and doing $(id).replace(data); with no success.
Don't ask me why, but that is what I need (I'm working with a special "mashup builder" site... it is a long story).
EDIT : I forgot to say that scripts in the received content have to be executed, even external scripts included using <script src="...">.
The simplest way is to set the new HTML content using:
document.open();
document.write(newContent);
document.close();
try this with jQuery:
$('body').load( url,[data],[callback] );
Read more at docs.jquery.com / Ajax / load
Here's how to do it in Prototype: $(id).update(data)
And jQuery: $('#id').replaceWith(data)
But document.getElementById(id).innerHTML=data should work too.
EDIT: Prototype and jQuery automatically evaluate scripts for you.
You could try doing
document.getElementById(id).innerHTML = ajax_response
the simplest way is
$("body").html(data);
Can't you just try to replace the body content with the document.body handler?
if your page is this:
<html>
<body>
blablabla
<script type="text/javascript">
document.body.innerHTML="hi!";
</script>
</body>
</html>
Just use the document.body to replace the body.
This works for me. All the content of the BODY tag is replaced by the innerHTML you specify.
If you need to even change the html tag and all childs you should check out which tags of the 'document.' are capable of doing so.
An example with javascript scripting inside it:
<html>
<body>
blablabla
<script type="text/javascript">
var changeme = "<button onClick=\"document.bgColor = \'#000000\'\">click</button>";
document.body.innerHTML=changeme;
</script>
</body>
This way you can do javascript scripting inside the new content. Don't forget to escape all double and single quotes though, or it won't work. escaping in javascript can be done by traversing your code and putting a backslash in front of all singe and double quotes.
Bare in mind that server side scripting like php doesn't work this way. Since PHP is server-side scripting it has to be processed before a page is loaded. Javascript is a language which works on client-side and thus can not activate the re-processing of php code.
I'm assuming you are using jQuery or something similar. If you are using jQuery, then the following should work:
<html>
<head>
<script src="jquery.js" type="text/javascript"></script>
</head>
<body>
content
</body>
<script type="text/javascript">
$("body").load(url);
</script>
</html>

addEventListener() not responding

I have written a small program to pop up an alert on click of a button using an addEventListener() . PFB the code below:
html file
<html>
<head>
<title>name alert</title>
<script type="text/javascript" src="test.js"></script>
</head>
<body>
<input id="p" type="button" value="alert">
</body>
</html>
javascript file
document.getElementById("p").addEventListener("click",greet,true);
function greet(){
alert("hello there !");
}
I dont get a pop up screen this way both the files are in the same folder btw.
test.js loads and executes before the DOM is loaded. So, at that point #p returns null. Try listening to onload event, and add click event.
document.addEventListener("DOMContentLoaded", function(){
document.getElementById("p").addEventListener("click",greet,true);
});
// global scope
function greet(){
alert("hello there !");
}
<input id="p" type="button" value="alert">
try to move your
<script type="text/javascript" src="test.js"></script>
just before
</body>
You need to put the addEventListener inside a function that is called on the load event. As the page is being created it will run the javascript as it comes to it. If it hasn't created the HTML yet, when the addEventListener runs it won't find the 'p' element and it will give you an error.
You can also move the javascript to be after the html, but it's more organized to put it in something like this:
<script type="text/javascript">
window.addEventListener('load', 'function(){pageload()}', false)
function pageload()
{
document.getElementById("p").addEventListener("click",greet,true);
}
</script>

HTML - Alert Box when loading page

i'm using HTML code and i wan't to show un Alert Message or alert box, i don't know what it is called, but a message with a "OK" button.
i want to show this alert when the page is loaded.
How do i do this?
And how to do this with a title in the Alert box?
Do I need JavaScript? if no, How to do this without javascript?
Jonathan
Yes you need javascript. The simplest way is to just put this at the bottom of your HTML page:
<script type="text/javascript">
alert("Hello world");
</script>
There are more preferred methods, like using jQuery's ready function, but this method will work.
You can use a variety of methods, one uses Javascript window.onload function in a simple function call from a script or from the body as in the solutions above, you can also use jQuery to do this but its just a modification of Javascript...Just add Jquery to your header by pasting
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.1.1/jquery.min.js"></script>
to your head section and open another script tag where you display the alert when the DOM is ready i.e. `
<script>
$("document").ready( function () {
alert("Hello, world");
});
</script>
`
This uses Jquery to run the function but since jQuery is a Javascript framework it contains Javascript code hence the Javascript alert function..hope this helps...
you need a tiny bit of Javascript.
<script type="text/javascript">
window.onload = function(){
alert("Hi there");
}
</script>
This is only slightly different from Adam's answer. The effective difference is that this one alerts when the browser considers the page fully loaded, while Adam's alerts when the browser scans part the <script> tag in the text. The difference is with, for example, images, which may continue loading in parallel for a while.
If you use jqueryui (or another toolset) this is the way you do it
http://codepen.io/anon/pen/jeLhJ
html
<div id="hw" title="Empty the recycle bin?">The new way</div>
javascript
$('#hw').dialog({
close:function(){
alert('the old way')
}
})
UPDATE : how to include jqueryui by pointing to cdn
<link rel="stylesheet" type="text/css" href="http://code.jquery.com/ui/1.10.0/themes/base/jquery-ui.css">
<script src="http://code.jquery.com/jquery-1.9.0.js"></script>
<script src="http://code.jquery.com/ui/1.10.0/jquery-ui.js"></script>
For making alert just put below javascript code in footer.
<script>
$(document).ready(function(){
alert('Hi');
});
</script>
You need to also load jquery min file.
Please insert this script in header.
<script type='text/javascript' src='https://code.jquery.com/jquery-1.12.0.min.js'></script>
<script type="text/javascript">
window.alert("My name is George. Welcome!")
</script>
<script>
$(document).ready(function(){
alert('Hi');
});
</script>
You can try this.
$(document).ready(function(){
alert();
$('#rep‌​ortVariablesTable tbody').append( '<tr><td>lll</td><td>lll</td></tr>');
});

Call vbscript function to run on body onload in all browsers

How can I get a vbscript function to run on body onload in all browsers?
This code (from w3schools) works in IE only:
<script type="text/vbscript">
function myFunction()
alert("Hello World!")
end function
</script>
</head>
<body onload="myFunction()">
I want to replace the alert with the code that is already written in vbscript and is working as is. Can this be accomplished using javascript?
Any help appreciated
Short answer is: you can't. To run cross-platform in the browser I recommend javascript.
Also, for code reference I would recommend MDN, rather than w3schools.
Just about everything can be accomplished with Javascript. My guess is that only IE supports VBScript in <script> tags, but I'm not positive on that.
Anyway, to do it in Javascript:
<script type="text/javascript">
function myFunction() {
alert("Hello World!");
}
</script>
The rest should be the same.

How to run JavaScript code before page load?

I have working in asp.net web application. Here I need to run JavaScript before page load.
I have tried:
<body oninit="funinit();" onprerender="funRender();" onload="funload();">
</body>
<script type="text/javascript" language="javascript">
function funinit() {
alert("funinit");
}
function funload() {
alert("funload");
}
function funRender() {
alert("funRender");
}
</script>
here only funload() is working.
You can use window.onpaint for such purpose like :
<script type="text/javascript">
function preloadFunc()
{
alert("PreLoad");
}
window.onpaint = preloadFunc();
</script>
I hope it helps you....
Just inline it?
<script type='text/javascript'>
alert("funload");
</script>
Or put it in a function and call it immediately. Try to put it to the topmost of your page, however since the DOM isnt loaded yet you cant get any other elements.
What is it you want to do?
just insert a <script> tag wherever inside the body you want it to run. it will be executed as soon as the parser reads it, as long as it doesn't reference an element not yet created
try to put your script in head section of the page:
<head>
<script type="text/javascript" language="javascript">
alert("funinit");
alert("funRender");
</script>
</head>
Why not Use the ClientScriptManager.RegisterClientScriptBlock Method
http://msdn.microsoft.com/en-us/library/btf44dc9.aspx

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