•  21-08-2019
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Question

How to make onclick without jQuery, with no extra code in HTML, such as:

<a href="#" onclick="tramtramtram">

Just using an external js file?

<script type="text/javascript" src="functions.js"></script>

I need to replace this code:

$("a.scroll-up, a.scroll-down").click(function(){
    SNavigate($(this).attr("href").substr(7));return false;
});
Was it helpful?

Solution

When this anchor will contain only one function to handle on click, than you can just write

document.getElementById('anchorID').onclick=function(){/* some code */}

otherwise, you have to use DOM method addEventListener

function clickHandler(){ /* some code */ }
var anchor = document.getElementById('anchorID');
if(anchor.addEventListener) // DOM method
  anchor.addEventListener('click', clickHandler, false);
else if(anchor.attachEvent) // this is for IE, because it doesn't support addEventListener
   anchor.attachEvent('onclick', function(){ return clickHandler.apply(anchor, [window.event]}); // this strange part for making the keyword 'this' indicate the clicked anchor

also remember to call the above code when all elements are loaded (eg. on window.onload)

-- edit

I see you added some details. If you want to replace the code below

$("a.scroll-up, a.scroll-down").click(function(){SNavigate($(this).attr("href").substr(7));return false;});

with sth that doesn't use jQuery, this should do the job

function addEvent(obj, type, fn) {
        if (obj.addEventListener)
                obj.addEventListener(type, fn, false);
        else if (obj.attachEvent)
                obj.attachEvent('on' + type, function() { return fn.apply(obj, [window.event]);});
}
addEvent(window, 'load', function(){
   for(var i=0, a=document.anchors, l=a.length; i<l;++i){
      if(a[i].className == 'scroll-up' || a[i].className == 'scroll-down'){
         addEvent(a[i], 'click', function(e){ SNavigate(this.href.substr(7)); e.returnValue=false; if(e.preventDefault)e.preventDefault();return false});
      }
   }
});

OTHER TIPS

how about this : 

document.getElementById("lady").onclick = function () {alert('onclick');};

W3C suggests: 

element.addEventListener('click',doSomething,false)

Microsoft uses:

element.attachEvent('onclick',doSomething)

You can do some feature detection and determine which call to use.

From http://www.quirksmode.org/js/events_advanced.html.

With no extra code in the html, here's a way to do it:

<html><body><head><script>  // This script could be in an external JS file
function my_handler(elt) {
    alert("Yay!");
    return false;
}

function setup() {
    document.getElementById('lady').onclick = my_handler;
}

window.onload = setup;
</script></head>
<body><a href='#' id='lady'>Test</a></body>
</html>

<script>
 function tramtramtram(){
     alert("tram it!");
 }
</script>


<a href="#" onclick="tramtramtram()">tramtram</a>

var el =document.getElementById('lady'); el.addEventListener( "click", tramtramtram, false );

Execute this script when document loads (replacing alert with your stuff):

var rgLinks = document.getElementsByTagName("A");

for (var x=0; x<rgLinks.length; x++) {
    el = rgLinks[x];

    if (el.className == 'scroll-down' || el.className == 'scroll-down')
        {
        el.onclick = function () {alert('onclick');};
        }
    }

Maybe that is what you are asking about...

Just use the onclick attribute. 

<a href="#" onclick="functionName(someParam)">

Or to do it from javascript, 

document.getElementById("anchorID").onclick = function(){
   some code
};

You need to use getElementById to add the onclick handler. However you need to initiate your code somewhere. Without jQuery you can only use the body onload handler:

<body onload="myinitfunction()">

myinitfunction can be in an external js file.

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