JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="m_ci" />
<input type="text" id="rp_ci" />

<input type="text" id="m_prueba1" />
<input type="text" id="rp_prueba1" />
<input type="text" id="m_prueba2" />
<input type="text" id="rp_prueba2" />

<input type="button" onclick="copy()" value="Copiar" />

JavaScript

function copyData(from,to)
{
    //var fields = ['nombre','apellido','profesion','ocupacion','direc_habi','telf_hab','direc_trab','telf_trab'];
    var fields = ['prueba1','prueba2'];
    
    var length = fields.length;    
    for(var i = 0;i<length;i++)
    {
         document.getElementById(to+fields[i]).value = document.getElementById(from+fields[i]).value;
    }
}

function copy()
{
    if(document.getElementById("m_ci").value==document.getElementById("rp_ci").value)
    {
           copyData('m_','rp_');
    }
}