Onclick() function on working

Question

all! I am having a problem using the a simple onclick method. Kindly please help me out. Here is that code... When i click on the button nothing really happens.

Answer 1

window.onload=initall();

calls the function initall and assigns the return value of initall as event handler. That is, initall is executed immediately and not when the load event is triggered.
Similar for btn.onclick=alert('hi');. But in both cases, the return value is not a function.

You have to assign functions to those properties, which are then being called when the event occurs.

function initall(){
    var btn = document.getElementById('btn');

    btn.onclick = function() { // creates and assigns the function at once
        alert('hi');
    };
}

window.onload = initall; // assign the function reference, no `()`.

I recommend to read the excellent tutorials at quirksmode.org to learn about event handling and of course the MDN JavaScript Guide for the JavaScript basics.