Develop Reference

Getting a Value from an Input Box and Assign it in a Variable using Javascript

Hi I'm just new to Javascript and I am trying to assign a value to a variable coming from the input box then access that variable in a loop. I have tried using document.getElementbyID('inputboxID').value; and document.getElementbyName('inputboxName').value; but it didn't work.
Here's my code:
<script>
var count = 0;
$(function(){
$('p#add_field').click(function() {
var num = document.getElementById('enfonum').value;
while (count < num) {
count +=1;
$('#container').append(
'<strong>Enforcer #'+count+'</strong><br/>'
+'<input id="field_ '+count+'"name="field[]'+'"type="text"/><br/>');
}
});
});
}
</script>
Here's the code for the input box:
<input type="text" id="enfonum" name="enfotxt"/>
and here's the code for the link that will trigger the script to be executed:
<p id="add_field">< a href="#"><span>» Add Enforcer</span></a></p>

You have to get value of enfonum input at run-time, not storing it at num var during initial page loading.
Here is the working sample with correct code:
var count = 0;
var num = document.getElementById('enfonum');
$('p#add_field').click(function () {
while (count < num.value) {
count += 1;
$('#container').append('<p><strong>Enforcer #' + count + '</strong><br/>'
+ '<input id="field_' + count + '" name="field[]' + ' "type="text"/><br/></p>');
}
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<p><input type="text" id="enfonum" name="enfotxt" /></p>
<p id="add_field"><span>» Add Enforcer</span></p>
<div id="container"></div>

The reason your code is not working, is simply that document.GetElementById does not exists, the correct syntax is document.getElementById.
Here's a jsfiddle with an example.
Good luck and good continuation,
Cheers !

Remove the extra } in the code, it will give you syntax error.
Tried it afterwards,the code works.
Syntax errors can break your javascript, it is wise to use plugins like firebug for firefox to fish out javascript errors.
Let me know if it works.

How do i rearrange the number in java script loop?

I have done the dynamic generates textbox based on the number that user type. For example, user types 10 in the input box clicked add will generate 10 input box. I have a label to catch the number.
here is my question
how do I start from 1?
how do I rearrange the number when user remove one of the input boxes
here is my javascript
$(document).ready(function () {
$("#payment_term").change(function () {
var count = $("#holder input").size();
var requested = parseInt($("#payment_term").val(), 10);
if (requested > count) {
for (i = count; i < requested; i++) {
$("#payment_term_area").append('<div class="col-lg-12 product_wrapper">' +
'<div class="col-lg-12 form-group">' +
'<label>' + i + 'Payment</label>' +
'<input type="text" class="payment_term form-control" name="PaymentTerm[]"/>' +
'</div>' +
'cancel' +
'</div>');
}
$("#payment_term_area").on("click", ".remove_field", function(e) { //user click on remove text
e.preventDefault();
$(this).parent('.product_wrapper').remove();
calculateTotal();
x--;
})
}
});
});
here is my view
<input type="text" id="payment_term" />
<button onclick="function()">Add</button>
<div id="payment_term_area"></div>

You were nearly there, however, by hardcoding the label's you were making updating them difficult for yourself. I have created a jsfiddle of my solution to your problems. I personally prefer to cache the values of my jQuery objects so that they arent hitting the DOM each time they are referenced, for the performance boost (hence why they are listed at the top). I also, find it nicer to bind the click event in JS rather than using the html attribute onclick, but this is just a preference.
JSFIDDLE
Javascript
// create cache of jQuery objects
var add_payment_terms_button = $('#add_payment_terms');
var payment_term_input = $('#payment_term');
var payment_term_area = $('#payment_term_area');
var default_payment_values = ['first value', 'second value', 'third value', 'forth value', 'fifth value'];
var default_other_value = 'default value';
// bind to generate button
add_payment_terms_button.on('click', generatePaymentTerms);
function generatePaymentTerms(){
var requested = parseInt(payment_term_input.val(), 10);
// start i at 1 so that our label text starts at 1
for (i = 1; i <= requested; i++) {
// use data-text to hold the appended text to the label index
payment_term_area.append(
'<div class="col-lg-12 product_wrapper">' +
'<div class="col-lg-12 form-group">' +
'<label data-text=" Payment"></label>' +
'<input type="text" class="payment_term form-control" name="PaymentTerm[]"/>' +
'</div>' +
'cancel' +
'</div>');
}
// call the function to set the labels
updateProductIndexes();
}
function updateProductIndexes(){
// get all labels inside the payment_term_area
var paymentLabels = payment_term_area.find('.product_wrapper label');
for(var x = 0, len = paymentLabels.length; x < len; x++){
// create jQuery object of labels
var label = $(paymentLabels[x]);
// set label text based upon found index + 1 and label data text
label.text( getOrdinal(x + 1) + label.data('text'));
// either set the next input's value to its corresponding default value (will override set values by the user)
label.next('input.payment_term').val(default_payment_values[x] || default_other_value)
// or optionally, if value is not equal to blank or a default value, do not override (will persist user values)
/* var nextInput = label.next('input.payment_term');
var nextInputValue = nextInput.val();
if(nextInputValue === '' || default_payment_values.indexOf(nextInputValue) >= 0 || nextInputValue === default_other_value){
nextInput.val(default_payment_values[x] || default_other_value)
} */
}
}
// courtesy of https://gist.github.com/jlbruno/1535691
var getOrdinal = function(number) {
var ordinals = ["th","st","nd","rd"],
value = number % 100;
return number + ( ordinals[(value-20) % 10] || ordinals[value] || ordinals[0] );
}
payment_term_area.on("click", ".remove_field", function(e) { //user click on remove text
e.preventDefault();
$(this).parent('.product_wrapper').remove();
// after we remove an item, update the labels
updateProductIndexes();
})
HTML
<input type="text" id="payment_term" />
<button id="add_payment_terms">Add</button>
<div id="payment_term_area"></div>

First you have to give id for each label tag ex:<label id='i'>
Then you can re-arrange the number by using document.getElementById('i')
Refer the Change label text using Javascript
hope this will be much helpful

Javascript For Loop keeps doubling up my divs

I have written a script that creates a number of fields based on a number the user inputs (k).
I originally wrote a script that would create the correct number of fields. However I wanted to arrange them like vectors on the screen, so I adapted my script.
I wanted the following script to create the correct number of fields and place them in DIVS, so I could lay them out as I wish on the page.
Since doing this, the script now produces duplicate DIVS as iff it runs through the loop twice, but I can't for life of me work out why...
function createFields(k)
{
k=k+1
for (var n=1; n<k; n++) {
var makeBox=document.createElement("div");
makeBox.id = "box" + n;
document.getElementById("top").appendChild(makeBox);
document.getElementById("box" + n).setAttribute('class',"box");
var addOpen=document.createElement("div");
addOpen.id = "open"+n;
document.getElementById("box" + n ).appendChild(addOpen);
document.getElementById("open" + n).setAttribute('class',"open");
var vectorBox=document.createElement("div");
vectorBox.id = "vector" + n;
document.getElementById("box" + n).appendChild(vectorBox);
document.getElementById("vector" + n).setAttribute('class',"vect");
var xVector=document.createElement("div");
xVector.id = "top" + n;
document.getElementById("vector" + n).appendChild(xVector);
document.getElementById("top" + n).setAttribute('class',"xVect");
var newx=document.createElement("input");
newx.id = "x" + n;
document.getElementById("top" + n).appendChild(newx);
document.getElementById("x" + n).setAttribute('name',"x" + n);
document.getElementById("x" + n).setAttribute('type',"text");
document.getElementById("x" + n).setAttribute('size',"4");
document.getElementById("x" + n).setAttribute('maxlength',"4");
var yVector=document.createElement("div");
yVector.id = "bottom" + n;
yVector.class = "yVect";
document.getElementById("vector" + n).appendChild(yVector);
document.getElementById("bottom" + n).setAttribute('class',"yVect");
var newy=document.createElement("input");
newy.id = "y" + n;
document.getElementById("bottom" + n).appendChild(newy);
document.getElementById("y" + n).setAttribute('name',"y" + n);
document.getElementById("y" + n).setAttribute('type',"text");
document.getElementById("y" + n).setAttribute('size',"4");
document.getElementById("y" + n).setAttribute('maxlength',"4");
var addClose=document.createElement("div");
addClose.id = "close"+n;
document.getElementById("box" + n ).appendChild(addClose);
document.getElementById("close" + n).setAttribute('class',"close");
}
}
Any clues?
UPDATED:
The Code is called via another function:
function getVectors()
{
v = document.getElementById("vectorN").value;
v=parseInt(v); //turn the text into an integer
document.getElementById("q1").innerHTML="Enter your Vectors below!";
createFields(v);
document.getElementById("enter").innerHTML="<input type=\"button\" id=\"button\" value=\"Submit Numbers\" onclick=\"canvas()\"/>";
}
Which is called by onchange in the html:
<p id="q1">How many Vectors will you need?
<input id="vectorN" name="vectorN" type="text" onChange="getVectors()" size="4" maxlength="4">
</p>
Further UPDATE
After checking the console.log,
the only place that calls createFields() is the getVectors() function. It does appear to be calling createFields twice (despite only doing so once in the script).
The ONLY place that calls getVectors() is the onChange event in the input field.
Is it possible that when I change the innerHTML and remove the input field that this is being registered as an onChange event and calling the function again?

Your function looks fine. aren't you just calling the function twice? Do a console.log right after function createFields(k) { to check if that's the case. Maybe 2 event listeners on the field where the user inputs k (onkeyup, change)?
If you're not sure where you call createFields from. Do a find in all files and look for createFields. Add a console.log('Calling createFields from here'); just before you call createFields.

This SO Question sheds some light on the problem. I'd been tabbing out of the text box, which only triggers the onChange event once. Pressing enter fires it twice, which is the problem you were getting.
There are a couple of ways to get around this. I've chosen to keep track of the number of fields entered. If this changes, generate the fields. If not do nothing.
var fields = 0;
function createFields(k) {
if (k != fields) {
fields = k;
console.log("Fields: " + k);
//Rest of the code the same;
}
}
Demo: http://jsfiddle.net/Ej8Ly/5/
You could also do something similar in the getVectors() function instead.

Rather than "creating" all the elements with the DOM why not build a "string" and then set a container objects .innerHTML = the_string value? This way it won't matter if the function gets called twice because it will simply overwrite itself the second time and produce the same output.

How do I make keep these values from rewriting into the HTML?

I have a small piece of code that is writing some values into a textarea inside a form. The write whenever I click a button. However if I click the button more than once they will write over and over. I need to be able to click the button multiple times (for example if the user changes a value) and have the values that I am writing simply refresh rather than repeat. Here is what I have...
var endwallPanelLengths = [totalHeightInches];
var i = 0;
while (endwallPanelLengths[i] > eaveInches)
{
endwallPanelLengths.push(endwallPanelLengths[i] - peakHeightDecrease);
document.getElementById("test83").value += "4 - " + endwallPanelLengths[i] + "\n";
i++;
}
When I click the button the first time the values are correct however they write again after everytome i click it?

In this line:
document.getElementById("test83").value += "4 - " + endwallPanelLengths[i] + "\n";
you're appending a value to test83. Presumably (since I can't see your html!!!) you just need to remove the + from the +=.
EDIT: in case you want to append all of the values in your loop, and nothing else, simply clear the value before you enter your loop and leave the +=
document.getElementById("test83").value = "";
var endwallPanelLengths = [totalHeightInches];
......

I think you want to do the whole iteration when the user change a value. Then you just need to reset the value of the textarea to empty before the loop. Something like this:
var endwallPanelLengths = [totalHeightInches];
var i = 0;
document.getElementById("test83").value = ''; //Reset the value
while (endwallPanelLengths[i] > eaveInches) {
endwallPanelLengths.push(endwallPanelLengths[i] - peakHeightDecrease);
document.getElementById("test83").value += "4 - " + endwallPanelLengths[i] + "\n";
i++;
}
I have worked out a demo page. Hope that is what you are after.

Try this:
var endwallPanelLengths = [totalHeightInches];
var i = 0;
document.getElementById("test83").value = '';
while (endwallPanelLengths[i] > eaveInches)
{
endwallPanelLengths.push(endwallPanelLengths[i] - peakHeightDecrease);
document.getElementById("test83").value += "4 - " + endwallPanelLengths[i] + "\n";
i++;
}
I'm assuming that all the code is executed eacht time you click the button, am I right ?

you need to implement a clickEventhandler that checks whether or not your texts exists.....

popualte textbox from values on screen with javascript

how can I use the values from the code below:
<html:select property="state" >
<html:option value="0">Select State</html:option>
<html:optionsCollection name="InputForm" property="stateList" label="label" value="value" />
</html:select>
to populate a textbox with whatever the selected value is for the state with a javascript onchange event? for example if texas is the selected state I want Texas to be written in the textbox and if I change the value to Colorado I would like Colorado and Texas to both show in the textbox. I am currently getting an undefined value in the textbox. I am using the following javascript code:
function displayState(obj, state) {
var theId = obj.id.substring(obj.id.indexOf('_') + 1);
var text = document.getElementById('text' + '_' + theId);
var textVal = text.value;
var stateSelect = document.getElementById('stateCode' + '_' + theId);
var stateSelectStr = new String(stateSelect.value);
var stateSelectSplit = stateSelectStr.split(',');
var stateSelectValue = stateSelectSplit[0];
var stateSelectLabel = stateSelectSplit[1];
if (stateSelectValue == '51') {
stateSelectLabel = '';
}
if (stateSelectValue != '00') {
textVal = textVal != '' ? eval('text.value=\'' + textVal + ', '
+ stateSelectLabel + '\'')
: eval('text.value=\'' + stateSelectLabel + '\'');
}
}

First off, start using jQuery (or equivalent), it will make your life much easier. Second, why are you using eval? You already have the text element; just build the appropriate string and set the value. See here for an example.
But again, using something like jQuery makes this laughably easy--I can't recommend using a library for simple DOM manipulation like this.
See here for a comparison between raw JS and JQ.