multiple functions called same time causing issue

[johnmerlino]

Hey all,

I have an application.js file. The javascript is just a typical hide/show tabs
effect, so when the user clicks on one link, the corresponding div is
revealed and the other divs are hidden. Two pages require the
javascript. However, while one page displays content of no tabs onload,
the other page displays the content of the first tab onload. So the page
that displays the content of no tab onload works fine. However, the page
that displays the content of first tab onload is not working. I get the
following error in FireBug:

document.getElementById("tabs") is NULL
var tabListItems = document.getElementById("tabs").childNodes;

I think the issue is I'm calling multiple functions on page load (and
hence since the one page doesn't have a tabs id it doesn't know what to
do), even though I only need one function for each of the pages. But I
would like to keep this tab effect in the same file. So I don't know what
to do. Thanks for anyone's response:

window.onload = init;

var tabLinks = new Array();
var contentDivs = new Array();

function init() {
  initProduct();
  initAbout();
}

function initProduct() {
  var tabListItems = document.getElementById("tabs").childNodes;
  for(var i=0; i < tabListItems.length; i++) {
    if(tabListItems[i].nodeName == "LI") {
      var tabLink = getFirstChildWithTagName(tabListItems[i], "A");
      var id = getHash(tabLink.getAttribute("href"));
      tabLinks[id] = tabLink;
      contentDivs[id] = document.getElementById(id);
      tabLinks[id].className = "";
      contentDivs[id].className = "tabContent hide";
      tabLinks[id].onclick = showTab;
      tabLinks[id].onfocus = function() { this.blur() };
    }
  }
}

function initAbout() {
  var tabListItems = document.getElementById("tabAbout").childNodes;
  for(var i=0; i < tabListItems.length; i++) {
    if(tabListItems[i].nodeName == "LI") {
      tabLink = getFirstChildWithTagName(tabListItems[i], "A")
      id = getHash(tabLink.getAttribute("href"));
      tabLinks[id] = tabLink;
      contentDivs[id] = document.getElementById(id);
    }
  }
  var i = 0;
  for(var id in tabLinks) {
    tabLinks[id].onclick = showTab;
    tabLinks[id].onfocus = function() { this.blur() }
    if(i == 0) {
      tabLinks[id].className = "selected"
    }
    i++
  }
  var i = 0;
  for(var id in contentDivs) {
    if(i != 0) {
      contentDivs[id].className = "tabContent hide";
    }
    i++
  }
}

function showTab() {
  document.getElementById("product").className = "tabContent hide"
  var selectedId = getHash(this.getAttribute("href"));

  for(id in contentDivs) {
    if(id == selectedId) {
      tabLinks[id].className = "selected";
      contentDivs[id].className = "tabContent";
    }
    else {
      tabLinks[id].className = "";
      contentDivs[id].className = "tabContent hide";
    }
  }

  return false;
}



function getFirstChildWithTagName(element, tagName) {
  for(var i=0; i < element.childNodes.length; i++) {
    if(element.childNodes[i].nodeName == tagName) {
      return element.childNodes[i];
    }
  }
}

function getHash(url) {
  var hashPos = url.lastIndexOf("#");
  return url.substring(hashPos + 1);
}

[Dormilich]

you can always check, if the element exists.

PHP Code:

function initProduct() {
  var tabList = document.getElementById("tabs");
  if (!tabList) {
    return false;
  }
// further code 


[johnmerlino]

Should this have made the error go away and make all tabs but selected one display:

function init() {
	initProduct();
	initAbout();
}

function initProduct() {
	var tabListItems = document.getElementById("tabs").childNodes;
	if (!tabListItems) {
		return false;
	}
	for(var i=0; i < tabListItems.length; i++) {
		if(tabListItems[i].nodeName == "LI") {
			var tabLink = getFirstChildWithTagName(tabListItems[i], "A");
			var id = getHash(tabLink.getAttribute("href"));
			tabLinks[id] = tabLink;
			contentDivs[id] = document.getElementById(id);
			tabLinks[id].className = "";
			contentDivs[id].className = "tabContent hide";
			tabLinks[id].onclick = showTab;
			tabLinks[id].onfocus = function() { this.blur() };
		}
	}
}

Because the error still displays and the other tabs still do not hide. So I'm wondering if there is something else wrong?

Thanks for any response.

[Dormilich]

Originally Posted by johnmerlino

Should this have made the error go away and make all tabs but selected one display:

it should make the error go away.

Originally Posted by johnmerlino

Because the error still displays and the other tabs still do not hide. So I'm wondering if there is something else wrong?

compare your code to mine and you’ll see what went wrong.

[johnmerlino]

Thanks, I see now.

[Dormilich]

another possibility would be

PHP Code:

function initProduct() {
    try {
        var tabListItems = document.getElementById("tabs").childNodes;
    }
    catch (e) {
        console.log(e.message); // <-- not IE compatible
        return false;
    }
// further code