getElementById没有在Javascript中选择元素

Question

I am trying to create an event based on the DOM for testing my Javascript skills, anyone knows why this isn't applying to the element?

function getButton(){
    var getButton = document.getElementById("submit");
    getButton.onclick() = function(){
         alert("it works!")
    }
}

Submit is an <input type="submit" /> type of element from the element by Id, so I don't get it why it wouldn't work.

Answer 1

Drop the () in the event identifier. You are just assigning a property here and do not make a function call or similar.

function getButton(){

  var getButton = document.getElementById("submit");

  getButton.onclick = function(){
     alert("it works!");
  }
}

Answer 2

getButton.onclick = function() {
       alert("it works!");
};

Answer 3

You have several problems in your code:

1. The element you're trying to submit is a <submit> tag; it doesn't have id="submit" , so trying to get the element getElementById("submit") isn't going to work.

   Either give your <submit> tag its own id and select by that, or use getElementByTagName("submit") instead.

2. As the @Sirko and @Osiris have mentioned, getButton.onclick() = function(){ isn't working because you're trying to call .onclick() as a function when it's not. What you want to do is to assign a function to the onclick attribute of getButton :

   getButton.onclick() = function(){ should be getButton.onclick = function(){ .