Pass javascript function as data-* attribute and execute

Question

We know such syntaxes as below, when defining a value for onClick attribute:

<button type="submit" onclick="alert('hi');"></button>
<button type="submit" onclick="doWork"></button> <!-- This one doesn't work -->
<button type="submit" onclick="doWork()"></button>
<button type="submit" onclick="doWork('Mike', 2)"></button>

What I'm interested in is to define a custom data-attribute and execute the value as follows:

<button type="submit" data-callback="alert('hi');"      class="marker"></button>
<button type="submit" data-callback="doWork"            class="marker"></button>
<button type="submit" data-callback="doWork()"          class="marker"></button>
<button type="submit" data-callback="doWork('Mike', 2)" class="marker"></button>

<script type="text/javascript">
    jQuery("body").on("click","button.marker", function(e) {
        var callback = jQuery(e.currentTarget).data("callback");

        // Now I need to execute the callback no matter of the format
        // 1. Execute as function's body
        // 2. Or by function 'name'
        // 3. Or by function 'name' with 0 parameters
        // 4. Or by function 'name' with n parameters
    })

    function doWork(name, nr){
        var personName = name || "Unnamed";
        var personNr = nr || 0;
        alert("Name is: " + personName + " Nr: " + personNr);
    }
</script>

I've pasted the sample to jsBin

How to accomplish same behaviour using custom data-attributes?

Answer 1

One way is to use eval()

jQuery(".container").on("click", "button.marker", function (e) {
    var callback = jQuery(e.currentTarget).data("callback");

    var x = eval(callback)
    if (typeof x == 'function') {
        x()
    }
});

Demo: Fiddle

Note: Make sure it is safe in your environment, ie there is no possibility of script injection because of bad input from users

• Why is using the JavaScript eval function a bad idea?
• When is JavaScript's eval() not evil?
• eval() isn’t evil, just misunderstood
• Eval is Evil, Part One

Answer 2

I think a better idea would be to dynamically bind the events and trigger them. If you wanted them to only be known by other code, you could use custom events.

<button type="submit" class="marker marker1"></button>
<button type="submit" class="marker marker2"></button>
<button type="submit" class="marker marker3"></button>
<button type="submit" class="marker marker4"></button>

<script>
    var $markers = $('.marker');
    $markers.filter('.marker1').bind('customCallback', function(){ alert("hi"); });
    $markers.filter('.marker2').bind('customCallback', function(){ doWork(); });
</script>

Then your other components could invoke them with $(selector).trigger('customCallback');

Answer 3

Simply with :

 $("body").on("click","button.marker", function(e) {
     eval($(this).data("callback"));
 })

Answer 4

If you really wanted to pass functions (with or without parameters) from one thing to another without binding them as events you could do it this way (I started from @Taplar's answer)

<button type="submit" class="marker marker1"></button>
<button type="submit" class="marker marker2"></button>
<button type="submit" class="marker marker3"></button>
<button type="submit" class="marker marker4"></button>

<script>
  var $markers = $('.marker');
  $markers.filter('.marker1').get(0).customCallback =  doWork;
  $markers.filter('.marker2').get(0).customCallback = function(){ 
    doWork(arg0,arg1); 
  };
</script>

Then you could access them in your other component as:

<script>
  $('.marker').each(function(){
    var  thisFunction = $(this).get(0).customCallback;
    //do something useful with thisFunction
  });
</script>

Answer 5

You can just bind a function as a data attribute

const ele = $('button');

ele.data('onClick', evt => {
    alert('bye');
})

ele.click(evt => {
    const ele = $(evt.target);
    ele.data('onClick')(evt);
})

Answer 6

Another way is using window[func](args).

Similar to the eval(), but you will have to store the function name and the argument separately in the HTML attribute.

Here is a quick example... CodePen

<button type="submit" data-func="Angel" data-args='use me instead of evil()' class="marker">TEST</button>

<script type="text/javascript">

    //=== The Listener =====
    $(".marker").on("click",function(){

        // Get the function name and arguments
        let func = $(this).attr("data-func");
        let args = $(this).attr("data-args");

        // Call the function
        window[func](args);
    })


    //=== The Function =====
    function Angel(msg){
        alert(arguments.callee.name + " said : " + msg);
    }
</script>