如何将jQuery代码转换为JavaScript？

Question

I want convert following working jQuery code into JavaScript

$(document).ready(function(){
    $("#txt1").keydown(function(event){
        var keyPress=String.fromCharCode(event.keyCode);
        var Keycode=event.keyCode;
        alert("KeyPress : "+keyPress)
        alert("KeyCode : "+Keycode)   
    })
})

and I am trying this to replace this code with JavaScript

document.getElementById("txt1").onkeydown=function(event){
    var keyPress=String.fromCharCode(event.keyCode);
    var Keycode=event.keyCode;
    alert("KeyPress : "+keyPress)
    alert("KeyCode : "+Keycode) 
}

and this above code not working.

Answer 1

Try this:

window.onload = function() {
  document.getElementById("txt1").addEventListener("keydown", function(e) {
    keyPress = String.fromCharCode(e.keyCode);
    keyCode = e.keyCode;    
    alert("KeyPress : " + keyPress)
    alert("KeyCode : " + keyCode)  
  }, false);
}