How to pass an event object to a function in Javascript?

Question

function check_me() {
  //event.preventDefault();
  var hello = document.myForm.username         


        

Answer 1

1. Modify the definition of the function check_me as::

    function check_me(ev) {
   

2. Now you can access the methods and parameters of the event, in your case:

    ev.preventDefault();
   

3. Then, you have to pass the parameter on the onclick in the inline call::

    Click Me!
   

A useful link to understand this.

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Full example:

  
    
  
  
    Click Me!
  

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Alternatives (best practices):

Although the above is the direct answer to the question (passing an event object to an inline event), there are other ways of handling events that keep the logic separated from the presentation

A. Using addEventListener:

  
  
  
    Click Me!

    
    
  

B. Isolating Javascript:

Both of the above solutions are fine for a small project, or a hackish quick and dirty solution, but for bigger projects, it is better to keep the HTML separated from the Javascript.

Just put this two files in the same folder:

• example.html:

  
  
  
    Click Me!

    
    
  

• example.js:

function check_me(ev) {
    ev.preventDefault();
    alert("Hello World!")
}
document.getElementById("my_button").addEventListener("click", check_me);