difference between alert(“Hi!”) and function(){alert(“Hi!”)} [duplicate]

Answer 1

alert('Hi') 

Here alert is an inbuilt function called by browser which opens a alert box.

function callAlert(){
  alert('Hi');
}

Here callAlert is a custom function which calls the inbuilt function alert

In your example, when appending a click event, you have to define the function

document.getElementById("myButton").onclick = alert('Hi!') //alert is 

already executed

document.getElementById("myButton").onclick = function (){ alert('Hi!') }; 
//a function is defined/declared which will be executed when the onclick action is performed