I am having trouble printing a simple array list in javascript. undefined is being printed before only two array items. please consider the code below;

function buildList(){
    var box = document.getElementById("box");
	var startList  = "<ol>";
	var endList = "</ol>";
	var listItems;
      
        var arry = ["Go to shopping", "Go to Mall"];
  	for(var i = 0; i < arry.length; i++){
            listItems += "<li>" + arry[i] + "</li>";
	}

	box.innerHTML = startList + listItems + endList;
}
document.onLoad(buildList());``
          

<div id="box">
  
</div>

I am having trouble printing a simple array list in javascript. undefined is being printed before only two array items. please consider the code below;

function buildList(){
    var box = document.getElementById("box");
	var startList  = "<ol>";
	var endList = "</ol>";
	var listItems;
      
        var arry = ["Go to shopping", "Go to Mall"];
  	for(var i = 0; i < arry.length; i++){
            listItems += "<li>" + arry[i] + "</li>";
	}

	box.innerHTML = startList + listItems + endList;
}
document.onLoad(buildList());``
          

<div id="box">
  
</div>

output of this is

undefined 1) Go to shopping 2) Go to Mall

Please help.

• javascript
• html
• arrays
• initialization
• undefined

Share Improve this question Follow edited Aug 14, 2015 at 20:39 Sarath Chandra 1,8862020 silver badges4040 bronze badges asked Aug 14, 2015 at 20:26 J AkhtarJ Akhtar 66711 gold badge99 silver badges2727 bronze badges 2

• You forgot to initialize listItems – Pointy Commented Aug 14, 2015 at 20:29
• Hi @knight, if any answer has solved your question please consider accepting it by clicking the check-mark. This indicates to the wider munity that you've found a solution and gives some reputation to both the answerer and yourself. There is no obligation to do this. – Sarath Chandra Commented May 6, 2016 at 11:32

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4 Answers 4

Sorted by: Reset to default 6

Your listItem variable is undefined because it is not initialized.

var listItems = "" ; (at line 5) should solve your problem.

You are declaring var listItems; => undefined, you should do as follows: var listItems = ""; => declared and initialized as an empty string.

You have to initialize listItems.

var listItems = "";

What you are doing right now is adding a string to listItems, but you did not define listItems. It does not know what is listItem

Try this. In your code you missing var listItems="";

Here is full code

function buildList()
       {
	   var box = document.getElementById("box");
	   var startList  = "<ol>";
	   var endList = "</ol>";
	   var listItems="";

	   var arry = ["Go to shopping", "Go to Mall"];

	    for(var i = 0; i < arry.length; i++)
	    {
		listItems += "<li>" + arry[i] + "</li>";
	   }

	  box.innerHTML = startList + listItems + endList;
      }

       document.onLoad(buildList());``
          

<div id="box">
  
  </div>