Javascript not declaring variables
Question
i'm new to JavaScript i have this script and i want to declare a variable on a if but on document.write , returns nothing what am i doing wrong ?
<head>
<script>
(function () {
setInterval(function () {
var NetworkStatus = document.getElementById("status"),
isOnline = navigator.onLine;
if (isOnline) {
NetworkStatus.innerHTML = "Online";
NetworkStatus.className = "online";
var person="John Doe";
} else {
NetworkStatus.innerHTML = "Offline";
NetworkStatus.className = "offline";
var person="Santa Claus";
}
}, 100);
})();
</script>
</head>
<body>
<h1 id="status"></h1>
<script>
document.write(person + "<br>");
</script>
</body>
4 answers
solution1
0 2013-11-26 12:06:39
You are in IIFE . which creates its own scope
And that's where it stays
Do this :
window.person="Santa Claus";
Instead of what you're doing.
solution2
0 2013-11-26 12:06:54
var sets the scope of the variable to the function it is declared within. You are trying to document.write it from outside that function, so it is out of scope and inaccessible.
Use window.person instead of var person .
solution3
0 2013-11-26 12:08:50
该函数在100毫秒后执行，这意味着页面加载时person变量没有值。
solution4
0 ACCPTED 2013-11-26 12:10:02
It's just all wrong, why use an IIFE and a timeout when all you have to do is add the script in the tag at the end of the DOM.
Also, you're setting the innerHTML of the element, and using document.write, which will overwrite the document ?
<head>
<title>I messed up</title>
</head>
<body>
<h1 id="status"></h1>
<script>
var NetworkStatus = document.getElementById("status"),
isOnline = navigator.onLine;
if (isOnline) {
var person = "John Doe";
NetworkStatus.innerHTML = "Online " + person;
NetworkStatus.className = "online";
} else {
var person = "Santa Claus";
NetworkStatus.innerHTML = "Offline " + person;
NetworkStatus.className = "offline";
}
</script>
</body>
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