Develop Reference

Javascript clientHeight returns NaN in certain contexts

Interesting issue arising for me.
I am working on an infinite scroll thing in javascript that requires getting clientHeight of a div at some point:
here is the code:
document.addEventListener('DOMContentLoaded', init, false);
function init(){
var j = 0;
var inner1 = document.getElementById("innerDiv1");
inner1.addEventListener("scroll", function(event){ window.j = 2; checkForLoad();});
var inner2 = document.getElementById("innerDiv2");
inner2.addEventListener("scroll", function(event){ window.j = 1; checkForLoad();});
}
var i = 0;
var checkForLoad = function() {
var bottomDiv;
var bottomDivChild;
var offsetOfDiv;
var offsetOfPage;
if(window.j === 2){
bottomDiv = document.getElementById("innerDiv1");
bottomDivChild = bottomDiv.lastElementChild;
offsetOfDiv = bottomDivChild.offsetTop + bottomDivChild.clientHeight; //WORKS FINE
offsetOfPage = (document.getElementById("innerDiv1").pageYOffset) + (document.getElementById("innerDiv1").clientHeight); //THIS IS WHERE THE ISSUE IS
}
else if(window.j === 1){
bottomDiv = document.querySelector("innerDiv2 > div:last-child");
offsetOfDiv = bottomDiv.offsetTop + bottomDiv.clientHeight;
offsetOfPage = inner1.pageYOffset + inner1.innerHeight;
}
if(offsetOfPage > offsetOfDiv - 10) {
alert("time to add");
//eventually will be AJAX with XSL
if (i % 5 !== 0) {
i++;
alert("into the append part");
var newResults = document.createElement("div");
newDiv.innerHtml = "testing " + i;
if(window.j === 2){
document.getElementById("innerDiv1").appendChild(newResults);
}
else if(window.j === 1){
document.getElementById("innerDiv2").appendChild(newResults);
}
checkForLoad();
} else if (i%5 === 0) {
newDiv = document.createElement("div");
newDiv.innerHTML = "Show more Results! " + i;
document.getElementById("scrollingDiv").appendChild(newDiv);
newDiv.setAttribute("ID", "showResults");
newDiv.setAttribute("onClick", "showMore()");
}
}
};
I realize that there are some inconsistencies here, but they are in parts of the script i am not using. Here is the issue though, in the if(window.j === 2) statement, you can see that I use client height in a couple places. In the first one, it returns a number perfectly and life goes on as planned, but when I use it in the line where I get the "offSerOfPage", the sum becomes NaN. I am using firebug to debug it and when I add document.getElementById("innerDiv1").clientHeight to the watch list, it shows that it has a number attatched to it. Yet the sum is returned as NaN. I think my wording is a bit confusing here so if you need clarification, please ask! Thanks!

assign parameter value of an object javascript

I have been looking at this code for a long time trying to figure this out, but I am having no luck. This issue is that I want to assign a value to the parameter boxId. When I click on a box in the webpage an alert will come up displaying that id. I have tried many things, but nothing seems to work. I'm a beginner, so I feel at this point there just must be something that I don't know how to do.
constructor function:
function Box (boxId, name, color, number, coordinates) {
this.boxId = boxId;
this.name = name;
this.color = color;
this.number = number;
this.coordinates = coordinates;
}
global variables:
var boxes = [];
var counter = 0;
var boxId = 0;
init function:
window.onload = init;
function init() {
var generateButton = document.getElementById("generateButton");
generateButton.onclick = getBoxValues;
var clearButton = document.getElementById("clearButton");
clearButton.onclick = clear;
}
function to get values and create new boxes:
function getBoxValues() {
var nameInput = document.getElementById("name");
var name = nameInput.value;
var numbersArray = dataForm.elements.amount;
for (var i = 0; i < numbersArray.length; i++) {
if (numbersArray[i].checked) {
number = numbersArray[i].value;
}
}
var colorSelect = document.getElementById("color");
var colorOption = colorSelect.options[colorSelect.selectedIndex];
var color = colorOption.value;
if (name == null || name == "") {
alert("Please enter a name for your box");
return;
}
else {
var newbox = new Box(boxId, name, color, number, "coordinates");
boxes.push(newbox);
counter++;
var boxId = counter;
}
addBox(newbox);
var data = document.getElementById("dataForm");
data.reset();
}
function that adds boxes to the page:
function addBox(newbox) {
for (var i = 0; i < newbox.number; i++) {
var scene = document.getElementById("scene");
var div = document.createElement("div");
div.className += " " + "box";
div.innerHTML += newbox.name;
div.style.backgroundColor = newbox.color;
var x = Math.floor(Math.random() * (scene.offsetWidth-101));
var y = Math.floor(Math.random() * (scene.offsetHeight-101));
div.style.left = x + "px";
div.style.top = y + "px";
scene.appendChild(div);
div.onclick = display;
}
}
function to display alert when box is clicked:
function display(e) {
var a = e.target;
alert(a.counter);
}
function to clear boxes:
function clear() {
var elems = document.getElementsByClassName("box");
for ( k = elems.length - 1; k >= 0; k--) {
var parent = elems[k].parentNode;
parent.removeChild(elems[k]);
}
}
All of the other functions work just fine. I keep running into the id showing up as "undefined" when I click it, or the counter displaying "0" in the console log, for everything I've tried.

You can do it like this.
First, in addBox() embed boxId as an tag's attribute like this:
div.setAttribute('data-boxId', newbox.boxId);
Then in display() you can retrieve it back:
alert(e.target.getAttribute('data-boxId'));
Please tell if you do not prefer this approach and I will post an alternative (closure things).
Edit: Add jsfiddle example http://jsfiddle.net/runtarm/8FJpU/

One more try. Perhaps if you change:
var boxId = counter;
to
boxId = counter;
It will then use the boxId from the outer scope instead of the one defined in the function getBoxValues()

how to use an event object to dispaly information about a DOM element

I want to be able to click on a box (the boxes are created through code, and receive values from a form) in the webpage and display information about the box. I am working on a display() function that uses an event object and an alert to display information about the box. So far, I've had multiple odd failures in my attempt to do this, which leads me to believe that I'm not accessing object attributes correctly. I'm a beginner, so this could be really obvious, but thanks for the help.
constructor function:
function Box (counter, name, color, number, coordinates) {
this.counter = counter;
this.name = name;
this.color = color;
this.number = number;
this.coordinates = coordinates;
}
Global variables:
var boxes = [];
var counter = 0;
Init function:
function init() {
var generateButton = document.getElementById("generateButton");
generateButton.onclick = getBoxValues;
var clearButton = document.getElementById("clearButton");
clearButton.onclick = clear;
}
Function that gets values from the form:
function getBoxValues() {
var nameInput = document.getElementById("name");
var name = nameInput.value;
var numbersArray = dataForm.elements.amount;
for (var i = 0; i < numbersArray.length; i++) {
if (numbersArray[i].checked) {
number = numbersArray[i].value;
}
}
var colorSelect = document.getElementById("color");
var colorOption = colorSelect.options[colorSelect.selectedIndex];
var color = colorOption.value;
if (name == null || name == "") {
alert("Please enter a name for your box");
return;
} else {
var newbox = new Box(counter, name, color, number, "coordinates");
boxes.push(newbox);
counter++;
/*for(m = 0; m < boxes.length; m++) {
counter.newbox = boxes[m];
}*/
}
addBox(newbox);
var data = document.getElementById("dataForm");
data.reset();
}
function that assigns attributes to the boxes:
function addBox(newbox) {
for (var i = 0; i < newbox.number; i++) {
var scene = document.getElementById("scene");
var div = document.createElement("div");
div.className += " " + "box";
div.innerHTML += newbox.name;
div.style.backgroundColor = newbox.color;
var x = Math.floor(Math.random() * (scene.offsetWidth-101));
var y = Math.floor(Math.random() * (scene.offsetHeight-101));
div.style.left = x + "px";
div.style.top = y + "px";
scene.appendChild(div);
div.onclick = display;
//console.log(newbox);
//shows all of the property values of newbox in the console
//console.log(div); shows that it is an object in the console
//console.log(div.hasAttribute(number)); says false
}
}
display function:
function display(e) {
// alert(e.target); says its an html object
//alert(e.target.className); works - says "box"
//alert(e.target.hasAttribute(name)); says false
}
I've included some of the things i've found in comments.

The event object only gives you the name not a reference to the element. So... a couple of things.
First if you want to be browser agnostic you want something like (e.srcElement is for IE):
var x = e.target||e.srcElement;
Then get a reference to the element and do what you want:
var refToElement = document.getElementById(x.id);

Javascript function not recognizing id in getElementById

I am adding a row to a table, and attached an ondblclick event to the cells. The function addrow is working fine, and the dblclick is taking me to seltogg, with the correct parameters. However, the var selbutton = document.getElementById in seltogg is returning a null. When I call seltogg with a dblclick on the original table in the document, it runs fine. All the parameters "selna" have alphabetic values, with no spaces, special characters, etc. Can someone tell me why seltogg is unable to correctly perform the document.getElementById when I pass the id from addrow; also how to fix the problem.
function addrow(jtop, sel4list, ron4list) {
var tablex = document.getElementById('thetable');
var initcount = document.getElementById('numrows').value;
var sel4arr = sel4list.split(",");
var idcount = parseInt(initcount) + 1;
var rowx = tablex.insertRow(1);
var jtop1 = jtop - 1;
for (j = 0; j <= jtop1; j++) {
var cellx = rowx.insertCell(j);
cellx.style.border = "1px solid blue";
var inputx = document.createElement("input");
inputx.type = "text";
inputx.ondblclick = (function() {
var curj = j;
var selna = sel4arr[curj + 2];
var cellj = parseInt(curj) + 3;
inputx.id = "cell_" + idcount + "_" + cellj;
var b = "cell_" + idcount + "_" + cellj;
return function() {
seltogg(selna, b);
}
})();
cellx.appendChild(inputx);
} //end j loop
var rowCount = tablex.rows.length;
document.getElementById('numrows').value = rowCount - 1; //dont count header
} //end function addrow
function seltogg(selna, cellid) {
if (selna == "none") {
return;
}
document.getElementById('x').value = cellid; //setting up for the next function
var selbutton = document.getElementById(selna); //*****this is returning null
if (selbutton.style.display != 'none') { //if it's on
selbutton.style.display = 'none';
} //turn it off
else { //if it's off
selbutton.style.display = '';
} //turn it on
} //end of function seltogg

You try, writing this sentence:
document.getElementById("numrows").value on document.getElementById('numrows').value
This is my part the my code:
contapara=(parseInt(contapara)+1);
document.getElementById("sorpara").innerHTML+="<li id=\"inputp"+contapara+"_id\" class=\"ui-state-default\"><span class=\"ui-icon ui-icon-arrowthick-2-n-s\"></span>"+$('#inputp'+contapara+'_id').val()+"</li>";
Look you have to use this " y not '.
TRY!!!!

Multiplying Variables Not Alerting

I have a script which calls variable values from input fields and multiplies them,
At the minute my function isnt executing, Im getting no alert neither, I think this is because of my if statement, can anybody see whats going wrong?
function Calculate() {
var ContentMinutes = document.getElementById ("ContentMinutes").value;
var ContentMinutesSelect = document.getElementById('ContentMinutesDD')
.options[document.getElementById('ContentMinutesDD').selectedIndex].value
if (ContentMinutesSelect == 0.0166)
{
var RenderingHours = 10;
var VideoHours = 5;
var VideoSeconds = 1;
document.getElementById("RenderHours").innerHTML=RenderingHours;
document.getElementById("VideoHours").innerHTML=VideoHours;
document.getElementById("VideoSeconds").innerHTML=VideoSeconds;
}
else if (ContentMinutesSelect == 0.0003)
{
var RenderingHours = 1540;
var VideoHours = 54;
var VideoSeconds = 1;
document.getElementById("RenderHours").innerHTML=RenderingHours;
document.getElementById("VideoHours").innerHTML=VideoHours;
document.getElementById("VideoSeconds").innerHTML=VideoSeconds;
}
else
{
var RenderingHours = 6410;
var VideoHours = 345;
var VideoSeconds = 124;
document.getElementById("RenderHours").innerHTML=RenderingHours;
document.getElementById("VideoHours").innerHTML=VideoHours;
document.getElementById("VideoSeconds").innerHTML=VideoSeconds;
}
var NoOfFrames = document.getElementById ("NoOfFrames").value;
//var EstimatedCoreHours = document.getElementById ("EstimatedCoreHours").value;
var ServiceLevel = document.getElementById('SerivceLevelDD')
.options[document.getElementById('SerivceLevelDD').selectedIndex].value;
var RenderHours = 1;
var CoresInTest = document.getElementById ("CoresInTest").value;
var EstimatedCoreHours = GetNumeric(NoOfFrames)
* GetNumeric(RenderingHours)
* GetNumeric(CoresInTest);
var EstimatedTotal = GetNumeric(ServiceLevel)
* GetNumeric(EstimatedCoreHours);
alert('Estimated Cost = '
+EstimatedTotal.toFixed(2)
+ 'Estimated Core Hours = '
+EstimatedCoreHours);
document.getElementById("EstimatedCoreHours").innerHTML =
EstimatedCoreHours.toFixed(2);
document.getElementById("EstimatedTotal").innerHTML =
EstimatedTotal.toFixed(2);
document.getElementById("EstimatedCoreHours").style.backgroundColor="yellow";
document.getElementById("EstimatedTotal").style.backgroundColor="yellow";
}
function GetNumeric(val) {
if (isNaN(parseFloat(val))) {
return 0;
}
return parseFloat(val);
}

if (ContentMinutesSelect == 0.0166) i think when you do .value you will get string result.
So your comparision should be
if (ContentMinutesSelect == "0.0166")

Your code will display no alert if any line before it results in an error , like if there isn't an element with the id 'ContentMinutes' in your document . The best way to debug would be to use something like firebug , or you could always put in a bunch of alerts and figure out what goes wrong.