Javascript variable undefined but alert outputs variable - javascript

I keep getting result is undefined but alert outputs result!
A bit puuzzling, the same thing happens in Chrome and IE.
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<form id="frm1" action="#" method="post">
Yammer ID: <input type="text" name="y_id"><br><br>
<input type="submit" onclick="myFunction()" value="Submit">
</form>
<p id="demo">uuu</p>
<script>
function myFunction() {
frm_i=document.getElementById("frm1");
result=frm_i.elements[0].value;
alert (result);
}
document.getElementById("demo").innerHTML = result;
</script>
</body>
</html>
I put:
document.getElementById("demo").innerHTML = result;
inside the function and i do not get an error, the uuu briefly changes to the input text then just as quickly changes back to uuu. But I get no error message this way.

Add var to frm_i and result and place:
document.getElementById('demo').innerHTML = result
Inside the function. It was out of scope.
Added a test server to verify success and changed #demo to an <output>
In order to prevent the form from refreshing after submitting, you can add the target attribute to the <form>:
<form id="frm1" action="http://httpbin.org/post" method="post" target='ifm'>
The value of target can be any location you have control over and '_blank' which is a new page (just like an anchor). If you prefer that the submit goes nowhere, then use:
target='#/'
In this Snippet, I submitted to the test server then redirected the response to a blank iframe by using the iframe's name attribute.
SNIPPET
<!DOCTYPE html>
<html>
<head>
</head>
<body>
<form id="frm1" action="http://httpbin.org/post" method="post" target='ifm'>
Yammer ID: <input type="text" name="y_id"><br><br>
<input type="submit" onclick="myFunction()" value="Submit">
<output id='demo'></output>
</form>
<iframe name='ifm' src='about:blank'></iframe>
<script>
function myFunction() {
var frm_i = document.getElementById("frm1");
var result = frm_i.elements[0].value;
alert(result);
document.getElementById("demo").innerHTML = result;
}
</script>
</body>
</html>

Related

error in printing the variable in javascript

When I'm running this code it is not showing me the message which I want to display (i.e: res).Suppose I'm giving an input "$code$".Can anyone just help me out?
<!DOCTYPE HTML>
<html>
<head>
</head>
<body>
<h1>Enter a sample message</h1>
<form>
<input type="text" name="a" id="a">
<button onclick="parse()">submit</button>
<p id="a"></p>
</form>
<script>
function parse(){
var msg=document.getElementById("a").innerHTML;
var res=msg.replace("$code$","1101");
document.getElementById("a").innerHTML=res;//this is to print res.
}
</script>
</body>
</html>
Two elements can't have the same ID. Further, an input element's value can not be obtained using the innerHTML property. Also, on clicking the submit button, the page will reload since the form get's submitted. To prevent that, call the function parse in an onsubmit on the <form> tag, and return false from the function.
<!DOCTYPE HTML>
<html>
<head>
</head>
<body>
<h1>Enter a sample message</h1>
<form onsubmit="return parse();">
<input type="text" name="a" id="a">
<button type="submit">submit</button>
<p id="b"></p>
</form>
<script>
function parse(){
var msg = document.getElementById("a").value;
document.getElementById("b").innerHTML = msg;
return false;
}
</script>
</body>
</html>
Check this:
<form>
<input type="text" name="a" class="input_field" id="a">
<button type="button" onclick="parse()">submit</button>
<p id="a"></p>
</form>
<script>
function parse(){
var msg=document.getElementById("a").innerHTML;
var form = document.getElementsByTagName("form")[0]
msg = form.getElementsByClassName("input_field")[0].value;//this is to print res.
}
</script>
I added type="button" to the button to prevent the form from reloading the page

Showing hidden input field with custom text

I have this text field hidden with HTML hidden code, now when the user enter an invalid input I use javascript to unhide the text field and display an error message, this is what is suppose to happen.
I have seen a lot of css style like
`style.visibility = 'visible';` and `style.display='block';`
But none of them are working for me what happens is that the error text shows for less than a second and then disappears, any one would like to share their thoughts.
This is the complete code for better understanding, it's still not working in firefox and Edge while IE and Chrome wont do anything, in Firefox, it just blinks once on each button press and that about it.
Javascript:
</script>
function validate(){
var firstname = document.getElementById("fn").value;
if (firstname == "") {
document.getElementById("fn").style.visibility = "visible";
document.getElementById("fn").text = "ERROR";
}
}
function init()
{
var formData = document.getElementById("enqForm");
formData.onsubmit = validate;
}
window.onload = init;
</script>
<!DOCTYPE html>
<html lang="en">
<head>
<script src="scripts.js"></script>
</head>
<body>
<form id="enqForm">
<input id="fn" type="text" placeholder="First Name *" />
<input id="sendbutton" type="submit" value="Enquire" />
</form>
</body>
</html>
Instead of changing the style, you can change the form's type attribute.
Using JavaScript - assuming you want to change lnspan to text:
document.getElementById('lnspan').type = 'text';
Style is not the same as the type attribute.
Also there's two id attributes in your <input>, you may want to change that.
**THAT IS THE ANSWER TO YOUR QUESTION**
<html>
<head>
<script>
function newDoc() {
document.getElementById("hid").type="text";
document.getElementById("hid").value="ERROR";
}
</script>
</head>
<body>
<input type="button" value="Load new document" onclick="newDoc()">
<input type="hidden" id="hid" value="">
</body>
</html>
<!--However this makes your error message as text field which is not good.
What you can do is make the Error into embedded into paragraph <p> so the
users cannot change it and it also looks more professional
<!DOCTYPE html>
<html>
<head>
<script>
function newDoc() {
document.getElementById("te").innerHTML="ERROR";
}
</script>
</head>
<body>
<input type="button" value="Load new document" onclick="newDoc()">
<p id="te">
</body>
</html>

Cannot change html content of div tag

I must not understand how to change the content of my <div> tag.
Here is my html file:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<script src="simple.js"></script>
<title>simple</title>
</head>
<body>
<div id="results" name="results"><!-- Results are displayed here -->
<form method="post" name="start">
<p>Enter url: <input type="text" name="myurl" size="100" /></p>
<button onclick="myFunction()">Click me</button>
</form>
</div>
</body>
</html>
Here is my .js file:
function myFunction() {
alert('hey');
document.getElementById("results").innerHTML = "Hello World";
}
When I click the button the alert pops up but the html does not change to "Hello World". It just stays the same :(
What am I doing wrong here.
Update: Thanks everyone! Here is what I have working now:
HTML:
<!DOCTYPE html>
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>simple</title>
</head>
<body>
<div id="results"><!-- Results are displayed here -->
<form method="post" name="start" target="_blank">
<p>Enter url: <input type="text" id="myurl" size="100" /></p>
</form>
<button id='clickme'>Click me</button>
<button id='noclickme'>No Click me</button>
</div>
<script src="simple.js"></script>
</body>
</html>
My .js file:
function say_something(s) {
document.getElementById("results").innerHTML = s;
}
document.getElementById("clickme").addEventListener("click", function(){
var url = document.getElementById('myurl').value;
if (url==null || url=="") { alert("Please supply a url"); return false; }
say_something( "Hello World [" + url + "]");
});
document.getElementById("noclickme").addEventListener("click", function(){
var url = document.getElementById('myurl').value;
if (url==null || url=="") { alert("Please supply a url"); return false; }
say_something( "Goodbye [" + url + "]");
});
A button's default behaviour is to submit the form. In this case, the action being blank, it will try to submit to the current URL. You need to prevent that from happening. Also it's bad form to put Javascript inside your HTML like that - use addEventListener instead:
document.querySelector("#results button").addEventListener("click", function(e) {
e.preventDefault();
alert('hey');
document.getElementById("results").innerHTML = "Hello World";
});
Note you'll need to include your script before the </body> rather than in <head> when using this method, or use the DOMContentLoaded event listener.
Example jsFiddle
The reason is the form label.
when you click the button, the form will take an action,but you did not have a certified action, so the chrome will take the defautl action,ie reload the html.
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<title>simple</title>
<script src="simple.js"></script>
</head>
<body>
<div id="results" name="results"><!-- Results are displayed here -->
<form method="post" name="start" target="_blank">
<p>Enter url: <input type="text" name="myurl" size="100" /></p>
<button onclick="myFunction()">Click me</button>
</form>
</div>
</body>
</html>

Can't receive value from input field

i have problem on sending textbox value from one html page to another html page.
In first page i am sending first name and last name values.and i want to catch this value in textbox on the second page( i.e home.html).but some erroe occurs.
error is :Uncaught TypeError: Cannot set property 'value' of null
how to solve? please tell me.
i know this stupid question.but please tell me guys.i don't know javascript.
this is my html code:
<!DOCTYPE html">
<html>
<head>
<script src="ttt.js"></script>
</head>
<body>
<form method="get" action="home.html" name="ff">
Firstname: <input id="f" type="text" name="firstname1">
Lastname: <input type="text" name="lastname">
<input type="submit">
</form>
</body>
</html>
this is my home.html code:
<!DOCTYPE html">
<html>
<head>
<script src="ttt.js"></script>
<script Language="JavaScript">
var tttt=val();
document.getElementById('text').value=tttt;
</script>
</head>
<body>
<form name="ff">
<input id="text" class="text" type="text" name="MyValue" value="helloS"/>
</form>
</div>
</body>
</html>
this is my javascript code(ttt.js)
function val(){
var link=location.href;
var str=link.split('?');
var str1=str[1].split('&');
var str11=str1[0].split('=');
var str12=str1[1].split('=');
var temp=str11[1]+" "+str12[1];
return(temp);
}
Put your javascript at the end of your html and change document.getElementById('tr') to document.getElementById('text'). You have no element with id tr.
please look at this question and its answers, it is demonstating how to pass value from one html page to another
link
You have to do getElementById('tr') when the dom is ready and ensuring that an element with the ID exists.

onclick event result disappears

When I use this code the console.log and the value in the field disappear right away.
window.onload = bereken;
function bereken(){
var knop = document.getElementById('berekenKnop').onclick = function (){
var aantalKm = document.getElementById('bereken');
console.log(aantalKm.value);
};
}
How can I prevent that from happening. Or what am I doing wrong?
The final goal will be to append the result of a calculation by the value of the field into another field.
edit:
<html>
<head>
<script src="bereken.js"></script>
</head>
<body>
<form id="berekenForm">
Bereken: <input type="text" name="bereken" id="bereken"/><br />
<input type="submit" value="Bereken" id="berekenKnop"/>
</form>
</body>
</html>
The submit button is doing its default task. i.e. submitting the form. Try handling that.
Value in the field 'bereken' not disappearing.See the code below. If this is not the expected answer, please, Update the question with question in details:
<html>
<head>
<script type="text/javascript">
window.onload = bereken;
function bereken(){
var knop = document.getElementById('berekenKnop').onclick = function (){
var aantalKm = document.getElementById('bereken');
console.log(aantalKm.value);
};
}
</script>
</head>
<body>
<div id="berekenKnop">
Click Here to console value
</div><br/>
<input type="text" value=" bereken value" id="bereken" />
</body>
</html>

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