单击函数中的按钮元素，JavaScript

Question

I have a problem with button in my code. I created two functions: szescian() and tabela(). szescian() is loading after clicking on picture and tabela() should be loading when clicking a button (with function szescian() is creating) by this code:

document.getElementById("przycisk").onclick = tabela();

, but when I'm clicking this image both functions are loading at the same time. What's the problem?

var br = document.createElement("br");
            var input = document.createElement("input");

function szescian(){

    var wynik = document.getElementById("wynik");

    var txt = document.createTextNode("Wpisz długość boku a:" );
    wynik.appendChild(txt);

    wynik.appendChild(br);

    input.type = "text";
    wynik.appendChild(input);

    var button = document.createElement("input");
    button.type = "button";
    wynik.appendChild(button);
    button.setAttribute("id", "przycisk");
    button.value = "Oblicz";

    document.getElementById("przycisk").onclick = tabela();


    }

    var a=input.value;
    var pol=a*a*a;
    var obj=a;

function tabela(){
  var wynik = document.getElementById("wynik");

  var tbl     = document.createElement("table");
  var tblBody = document.createElement("tbody");

 ....

Answer 1

You should give the function reference , not the return value. Remove the () :

document.getElementById("przycisk").onclick = tabela;