Why am I getting undefined output Javascript?
Question
I keep getting undefined before my output text in JS. Here is my code.
<!DOCTYPE html>
<html>
<head>
<link rel="stylesheet" type="text/css" href="css/style.css">
<meta charset="utf-8">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Learning javascript</title>
</head>
<body>
<p id="arrayString"></p>
<!-- Javascript -->
<script type="text/javascript" src="JS/app2.js"></script>
</body>
</html>
This is my JS
var arrayString;
var myArray=["Ms.Vickies", "Old Dutch", "Lays"];
for (var i=0; i<myArray.length; i++) {
arrayString=arrayString+myArray[i];
}
document.getElementById("arrayString").innerHTML=arrayString;
my output is undefinedMs.VickiesOld DutchLays
In addition why no spaces? I am new to JS but am working my way up. Cannot figure this out.
3 answers
solution1
7 2015-01-07 13:59:55
It's because in your first loop iteration, arrayString is undefined. Set it equal to an empty string instead.
Instead of declaring arrayString like so:
var arrayString;
Initialize it with an empty string:
var arrayString = '';
solution2
1 2015-01-07 14:02:10
Because you are initiating a null/undefined variable by doing this: var arrayString;
You can fix it by doing this: var arrayString = "";
Better yet, instead of using a for loop, you can do it like this:
var myArray=["Ms.Vickies", "Old Dutch", "Lays"];
document.getElementById("arrayString").innerHTML = myArray.join(" ");
solution3
0 2015-01-07 14:06:03
In code ,you have just declared,not initialized.so,just replace
var arrayString;
with
var arrayString = '';
Hope it helps...Thank you.
The technical post webpages of this site follow the CC BY-SA 4.0 protocol. If you need to reprint, please indicate the site URL or the original address.Any question please contact:yoyou2525@163.com.