将Javascript DOM值传递给内部HTML

Question

i need to get some value from one hidden id and pass it to another ID as inner HTML.

here my code

<script>
function replaceText(){
var x=document.getElementById("mainTitle1").value;
document.getElementById("mainTitle").innerHTML=x;
}
</script>

Here HTML File

<span id="mainTitle"></span>

<span style="display:none;" id="mainTitle1">Text Content</span>

but this isn't working. I'm getting 'undefined'

Answer 1

<script>
function replaceText(){
var x=document.getElementById("mainTitle1").innerHTML;   //Correct here 
document.getElementById("mainTitle").innerHTML=x;
}
</script>

The Problem is with .value change it to .innerHTML

Answer 2

GetElementById应该为getElementById JavaScript是区分大小写的语言

Answer 3

easy :

var x=document.getElementById("mainTitle1").innerHTML;
document.getElementById("mainTitle").innerHTML=x;

Working DEMO