[javascript] How to Call a JS function using OnClick event



Answers

You could use addEventListener to add as many listeners as you want.

  document.getElementById("Save").addEventListener('click',function ()
    {
     alert("hello");
     //validation code to see State field is mandatory.  
    }  ); 

Also add script tag after the element to make sure Save element is loaded at the time when script runs

Rather than moving script tag you could call it when dom is loaded. Then you should place your code inside the

document.addEventListener('DOMContentLoaded', function() {
    document.getElementById("Save").addEventListener('click',function ()
    {
     alert("hello");
     //validation code to see State field is mandatory.  
    }  ); 
});

example

Question

I am trying to call my JS function that I added in the header. Please find below code that shows my problem scenario. Note: I don't have access to the body in my application. Everytime I click on the element with id="Save" it only calls f1() but not fun(). How can I make it call even my fun()? Please help.

  <!DOCTYPE html>
  <html>
  <head>

  <script>

   document.getElementById("Save").onclick = function fun()
    {
     alert("hello");
     //validation code to see State field is mandatory.  
    }   

    function f1()
    {
       alert("f1 called");
       //form validation that recalls the page showing with supplied inputs.    
    }

  </script>
  </head>
  <body>
  <form name="form1" id="form1" method="post">
            State: 
            <select id="state ID">
               <option></option>
               <option value="ap">ap</option>
               <option value="bp">bp</option>
            </select>
   </form>

   <table><tr><td id="Save" onclick="f1()">click</td></tr></table>

   </body>
   </html>



function validate() {

    if( document.myForm.phonenumber.value == "" ) {
        alert( "Please provide your phonenumber!" );
        phonenumber.focus;
        return false;
    }
    if (/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,3})+$/.test(myForm.email.value))  {  
        return (true)  
    }  
    alert("You have entered an invalid email address!");
    return (false);
}



Using onclick attribute or apply a function to your JS onclick properties will erase your onclick initialization in .

What you need to do is add click events on your button. To do that you'll need addEventListener and attachEvent (ie) methods.

<!DOCTYPE html>
<html>
<head>
    <script>
        function addEvent(obj, event, func) {
            if (obj.addEventListener) {
                obj.addEventListener(event, func, false);
                return true;
            } else if (obj.attachEvent) {
                obj.attachEvent('on' + event, func);
            } else {
                var f = obj['on' + event];
                obj['on' + event] = typeof f === 'function' ? function() {
                    f();
                    func();
                } : func
            }
        }

        function f1()
        {
            alert("f1 called");
            //form validation that recalls the page showing with supplied inputs.    
        }
    </script>
</head>
<body>
    <form name="form1" id="form1" method="post">
        State: <select id="state ID">
        <option></option>
        <option value="ap">ap</option>
        <option value="bp">bp</option>
        </select>
    </form>

    <table><tr><td id="Save" onclick="f1()">click</td></tr></table>

    <script>
        addEvent(document.getElementById('Save'), 'click', function() {
            alert('hello');
        });
    </script>
</body>
</html>



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