Develop Reference

Cannot read property 'value' of null on simple var assignment: var goToThis = "";

I'm getting a javascript error Cannot read property 'value' of null on simple var assignment var goToThis = "";
// It is the second function that has the error.
function nextFocus(tLast) {
var goToThis = "";
var val = 0;
if(tLast === 'activity') {
if(document.getElementById('[Slip]Note').value === "") {
document.getElementById('[Slip]Note').value = document.getElementById('[Slip]Activity').value;
}
}
if((tLast === 'activity') && (fLedes === true)){
document.getElementById('[Slip]Task No').focus();
} else if((tLast === 'activity') && (fLedes === false)){
goToThis = 'billableHrs';
} else if(tLast === 'expense'){
goToThis = 'priceAdjustment';
} else if((tLast === 'task') && (initialSlipType === 'time')){
goToThis = 'billableHrs';
} else if((tLast === 'task') && (initialSlipType === 'expense')){
goToThis = 'priceAdjustment';
}
if(goToThis === 'billableHrs') {
val = getReal(document.getElementById("[Slip]Billable Hrs"));
if(val === 0) {
document.getElementById("[Slip]Billable Hrs").value = '';
//alert('[Slip]Billable Hrs: '+val);
}
document.getElementById('[Slip]Billable Hrs').focus();
} else if (goToThis === 'priceAdjustment') {
val = getReal(document.getElementById("[Slip]Price Adjustment"));
if(val === 0) {
document.getElementById("[Slip]Price Adjustment").value = '';
//alert('[Slip]Price Adjustment: '+val);
}
document.getElementById('[Slip]Price Adjustment').focus();
}
}

This error was solved by correcting the spelling of an HTML element involved with this function call.
Safari pointed to the correct error line.
Chrome would not point to the correct error line.

Check opening and closing curly braces {} on all functions of the page. Sometimes {} mismatch ,also gives weird errors. Also try '' instead of "";

if statements being skipped even when both expressions are true

I have a webpage that populates a table with arrays. It has a doClick function so that when a user clicks on a cell it passes the row and column of the cell to the function. Example cell: onclick="doClick(0,1)"
function doClick(row, col)
{
var top = row -1;
var bottom = row +1;
var left = col -1;
var right = col +1;
var swapped = false;
if ((top != -1) && (cells[top][col].innerHTML = ""))
{
cells[top][col].innerHTML = cells[row][col].innerHTML;
cells[row][col].innerHTML = "";
swapped = true;
}
else if ((right != 4) && (cells[row][right].innerHTML = ""))
{
cells[row][right].innerHTML = cells[row][col].innerHTML ;
cells[row][col].innerHTML = "";
swapped = true;
}
else if ((bottom != 4) && (cells[bottom][col].innerHTML = ""))
{
cells[bottom][col].innerHTML = cells[row][col].innerHTML;
cells[row][col].innerHTML = "";
swapped = true;
}
else if ((left != -1) && (cells[row][left].inn = ""))
{
cells[row][lef].innerHTML = cells[row][col].innerHTML;
cells[row][col].innerHTML = "";
swapped = true;
}
else
{
alert("Illegal Move.");
}
. The problem is, even if both if expressions are true, the if statement is being skipped and it's falling through to the else statement. I've desk checked it and run it through the developer tools and checked values. A statement that was true on both expressions was skipped. Any suggestions?

cells[row][right].innerHTML = ""
is wrong. You are missing the double (triple) =.
The correct way should be...
cells[row][right].innerHTML === ""

It looks like maybe there are a few typos or misconceptions in your code.
A quick note about Conditions in an IF statement
A statement like (cells[top][col].innerHTML = "") as a condition will always return true as this is setting cells[top][col].innerHTML as "" or at least instantiating the variable. So, the proper condition to test absolutely true or false would be (cells[top][col].innerHTML === ""). However, you can get away with not even doing that and simply replace (cells[top][col].innerHTML = "") with cells[top][col].innerHTML. You may run into some other issues though is the variable is not instantiated already, either way. I would wrap the latter logic in an IF statement to check if cells[top][col].innerHTML is even instantiated.
To fix this, check out the following modifications I have made to your code.
function doClick(row, col)
{
var top = row -1;
var bottom = row +1;
var left = col -1;
var right = col +1;
var swapped = false;
if(typeof cells[top][col].innerHTML !== 'undefined' $$ cells[top][col].innerHTML !== null)
{
if ((top != -1) && cells[top][col].innerHTML !== '')
{
cells[top][col].innerHTML = cells[row][col].innerHTML;
cells[row][col].innerHTML = "";
swapped = true;
}
else if ((right != 4) && cells[row][right].innerHTML !== '')
{
cells[row][right].innerHTML = cells[row][col].innerHTML ;
cells[row][col].innerHTML = "";
swapped = true;
}
else if ((bottom != 4) && (cells[bottom][col].innerHTML))
{
cells[bottom][col].innerHTML = cells[row][col].innerHTML;
cells[row][col].innerHTML = "";
swapped = true;
}
else
{
alert("Illegal Move.");
}
}
else if (typeof cells[row][left].inn !== 'undefined' && (left != -1) && cells[row][left].inn !== '')
{
cells[row][lef].innerHTML = cells[row][col].innerHTML;
cells[row][col].innerHTML = "";
swapped = true;
}
else
{
alert("Illegal Move.");
}
}
An example working to demonstrate the above code
var testVar1 = '';
var testVar2 = 'Hello';
// var testVar3; <- Left this un-instantiated to test existance
// Testing if a var is empty but exists
if(typeof testVar1 !== 'undefined' && testVar1 !== null){
if(testVar1 !== ''){
alert('testVar1 has a value!');
}{
alert('testVar1 does not have a value!');
}
}
// Testing if a var is empty but exists
if(typeof testVar2 !== 'undefined' && testVar2 !== null){
if(testVar2 !== ''){
if(testVar2 === 'Hello'){
alert('testVar2 has a value! Value: ' + testVar2);
}{
alert('testVar2 has a value but it is not the one we expected.');
}
}{
alert('testVar2 does not have a value!');
}
}
// Test existance
if(typeof testVar3 !== 'undefined' && testVar3 !== null){
alert('testVar3 exists!');
}else{
alert('testVar3 does not exist!');
}

Error: '0.type' is null or not an object in javascript

I am getting the error below when I click the button that calls the JavaScript to do the validation. The strange thing is that everything was working before but I am not what happened now. If I select to ignore this error:
Error: '0.type' is null or not an object
then the code works fine but I get the error first then it asks me if i want to debug it, if i select No then the code works fine. Please help. thanks
it seems the code stops at this line:
if (areas[0].type == "textarea") {
but here is my entire code:
<script type ="text/javascript">
function Validate_1() {
var flag = false;
var gridView = document.getElementById('<%= GridView1.ClientID %>');
for (var i = 1; i < gridView.rows.length; i++) {
var selects = gridView.rows[i].getElementsByTagName('select');
//var inputs = gridView.rows[i].getElementsByTagName('input');
var areas = gridView.rows[i].getElementsByTagName('textarea');
if (selects != null && areas != null) {
if (areas[0].type == "textarea") {
var txtval = areas[0].value;
var selectval = selects[0].value;
if (selectval == "No" && (txtval == "" || txtval == null)) {
flag = false;
break;
}
else {
flag = true;
document.getElementById('<%=btnSubmit.ClientID%>').style.visibility = 'visible';
}
}
}
}
if (!flag) {
alert('Please note that comments are required if you select "No" from the dropdown box. Thanks');
document.getElementById('<%=btnSubmit.ClientID%>').style.visibility = 'hidden';
// areas[i].focus();
// areas.[i].style.backgroundColor = "red";
}
return flag;
}
// document.getElementById('<%=btnSubmit.ClientID%>').style.visibility = 'visible';
</script>

var areas = gridView.rows[i].getElementsByTagName('textarea');
getElementsByTagNane does not return null, the length would be zero
So your if check needs to change.
if (selects != null && areas != null)
should be
if (selects.length && areas.length)

If conditions is not working in javascript injection

I am working on a project where i want to change the value of the desired text boxes in the web page.
I am using javascript injection to the web browser to paste the values of the text fields.
In the code below, I have taken a activeElement in the document and compare it with other element in the element List. and want to paste another string in the next text field. But in the below code the if----elseif--- condition is not working as desired.
var editcount = document.getElementsByTagName('input');
var fcElement = document.activeElement;
var cpt = 0;
var bFlag = false;
for (cpt = 0; cpt < editcount.length; cpt++) {
if (editcount[cpt].id == fcElement.id && !bFlag) {
fcElement.value = "Username";
bFlag = true;
}
else if((editcount[cpt].type == "password"||editcount[cpt].type == "text" || editcount[cpt].type == "email") && bFlag === true) {
editcount[cpt].value = "Password";
break;
}
}
Here, the password is also copied on the same text field.
can anyone tell me whats wrong with the script ?

Thank you for your help.
I was having problem with my code.
I was comparing the ids of the two elements.
if (editcount[cpt].id == fcElement.id && !bFlag)
and this was not working for some web pages but now I got the solution for it.
I have changed the condition of comparision of elements as below.
if (editcount[cpt].name == fcElement.name && !bFlag)
and My problem has solved.
I am posting my working code here...
`
var editcount = document.getElementsByTagName('input');
var fcElement = document.activeElement;
var cpt = 0;
var bFlag = false;
console.log(fcElement);
for (cpt = 0; cpt < editcount.length; cpt++) {
console.log(editcount[cpt]);
if (editcount[cpt].name == fcElement.name) {
fcElement.value = "Username";
bFlag = true;
} else if ((editcount[cpt].type == "password" || editcount[cpt].type == "text" || editcount[cpt].type == "email") && bFlag === true) {
editcount[cpt].value = "Password";
break;
}
}`
Thank you for your cooperation.
Merry Christmas.

form validation with radio buttons and specific errors

I am trying to make a form validate where there are radio buttons and textarea. I want nothing to be left empty i.e the form should be completely filled. I have done the radio buttons part of validation where if a user does not select a radio button he will get an error for that particular question. you can see the code here for detailed code.
Please help me out. I am not getting error for textarea.

Just add another check for textarea
function RadioValidator() {
var ShowAlert = '';
var AllFormElements = window.document.getElementById("FormID").elements;
for (i = 0; i < AllFormElements.length; i++) {
var name = AllFormElements[i].name;
if (AllFormElements[i].type == 'radio') {
....
} else if (AllFormElements[i].type == 'textarea') {
if (AllFormElements[i].value == '') {
ShowAlert += name + ' textarea must be filled\n';
}
}
}
if (ShowAlert !== '') {
alert(ShowAlert);
return false;
} else {
return true;
}
}

you didn't write any validation for 'textarea' block. I have updated it with one textarea... add rest validations.
function RadioValidator()
{
var ShowAlert = '';
var AllFormElements = window.document.getElementById("FormID").elements;
for (i = 0; i < AllFormElements.length; i++)
{
if (AllFormElements[i].type == 'radio')
{
var ThisRadio = AllFormElements[i].name;
var ThisChecked = 'No';
var AllRadioOptions = document.getElementsByName(ThisRadio);
var problem_desc = document.getElementById("problem_desc");
for (x = 0; x < AllRadioOptions.length; x++)
{
if (AllRadioOptions[x].checked && ThisChecked === 'No' && problem_desc.value === "")
{
ThisChecked = 'Yes';
break;
}
}
var AlreadySearched = ShowAlert.indexOf(ThisRadio);
if (ThisChecked == 'No' && AlreadySearched == -1 && problem_desc.value === "")
{
ShowAlert = ShowAlert + ThisRadio + ' option must be selected\n';
}
}else if(AllFormElements[i].type =='textarea')
{
// add your rest of text area validations here
var problem_desc_1 = document.getElementById("problem_desc");
if(problem_desc_1.value === "")
{
ShowAlert = ShowAlert + '"Services (Please Specify)" can not be blank. \n';
}
}
}
if (ShowAlert !== '')
{
alert(ShowAlert);
return false;
}
else
{
return true;
}
}

You need to add a check for textarea as well
In your javascript check you have only added a condition for type radio.
check for textarea type as well and add error if the value is blank.