如何通过JavaScript中的函数更改文本？

Question

我正在尝试获取文本，但是此文本已由made的功能更改。更改后，我无法再获取文本，返回值为NULL。

我尝试使用innerText，innerHTML和textContent，但是都返回null。 我不会发布所有HTML，因为它太大了

//HTML
<h2 id = "p1">PLAYER ONE</h2>//Text that I will change

<img src = "imagens/docinho.png" alt = "1.Docinho" class = "ppg" id = "d1" onclick="avatar(this.id);">
<img src = "imagens/florzinha.png" alt = "2.Florzinha" class = "ppg" id = "f1" onclick="avatar(this.id);">
<img src = "imagens/lindinha.png" alt = "3.Lindinha" class = "ppg" id = "l1" onclick="avatar(this.id);">

当我单击其中之一时，会得到默认文本并更改h2的文本

//JAVASCRIPT
//First change
function avatar(i)
{
    var textAlt = document.getElementById(i).alt;
    var aux = document.getElementById(i);
    var meuId = aux.id;

    document.getElementById('p1').innerHTML= textAlt;
}

//When I try get the new text in other function
//It's called by 'onClick'
function joga(celula)
{
   if(document.getElementById('p1').innerHTML == "1.Docinho")//Here i try to see whats is inside
   {
     O.style.backgroundImage = "url('imagens/3.jpg')";
   }
}