Change content of span by id

Question

I am trying to change john to mike. I have no idea why its not working.

<span id="user">John</span>

I am trying this but not working i have no clue why not working.

function set() {
    document['getElementById']('user')['value'] = Owner; 
    // owner value is mike
}

Answer 1

If you want to change the id, use

 document['getElementById']('user').id = 'mike'; 

or, more classically,

 document.getElementById('user').id = 'mike'; 

If you want to replace "John" (that is not the ID but the content of the span), do

 document.getElementById('user').innerHTML = 'mike'; 

Answer 2

function set() {
    document.getElementByID('user').innerHTML = Owner; 
    // owner value is mike
}

Answer 3

try:

function set() {
    document.getElementById('user').innerText= Owner; 
    // owner value is mike
}

Where is Owner declared, is it valid in your function scope?