Select GridView line with checkbox

    function Selecionar(elemento,cordefundo)
        {
            var Inputs = elemento.getElementsByTagName("input");
            var cor = elemento.style.backgroundColor; //manter a cor default do elemento
            for(var i = 0; i < Inputs.length; ++i)
            {
                if(Inputs[i].type == 'checkbox')
                {
                    Inputs[i].checked = !Inputs[i].checked;
                    elemento.style.backgroundColor = cordefundo;
                    elemento.onclick = function()
                    {
                        Selecionar(this,cor);
                    };         
                }         
            }       
        }

protected void gvSelecao_PreRender(object sender, EventArgs e){
        GridView gv = (GridView)sender;
        foreach (GridViewRow row in gv.Rows)
            row.Attributes.Add("onclick", "Selecionar(this,'#FFFF00');");
        }

I took these two codes from a website to make you select gridview rows by clicking on them.

This part I did not understand

 elemento.onclick = function()
                {
                    Selecionar(this,cor);
                };         

Why does he call the function again? Actually I understand, call the function again because it is part of the logic: it returns the default color of the line and unchecks the ckbox.

But I do not understand, because for me when the function was called it was closed, but when debugging I saw that when I click again on the line it falls directly into that part of the function:

elemento.onclick = function () {
                        Selecionar(this, cor);
                    };

What I found a mystery, because as I said, for me the function was called and closed. I took a print of what appears when I click again on the line:

Does anyone explain to me how this works? Why does not the function terminate? If they were several functions, would they remain open?