JQuery check if variable is function

This question already has an answer here:

How to execute a JavaScript function when I have its name as a string 29 answers

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In your example, to get a reference to the testFunction if it is in scope, you can use eval . Yes, I said it, eval , so you have to know that the string could be manipulated by the user to run malicious code if you don't sanitize it for function names;

var testController = function() {
  alert('123');
}

$(function() {
  $('[mfour]').each(function(e, t) {
    var a = eval($(t).attr('mfour'));
    console.log($.isFunction(testController));
    console.log($.isFunction(a));
  })
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/2.1.1/jquery.min.js"></script>
<div mfour="testController">Hello</div>

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Try using window[varname] - assuming the function is in global scope

like this

DEMO

var testController = function() {
    alert('123');
}

$(function() {
    $('[mfour]').each(function(e, t) {
        var a = $(t).attr('mfour');
        console.log($.isFunction(testController));
        console.log($.isFunction(window[a]));
        console.log(typeof window[a] === "function");
    })
});

<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.11.1/jquery.min.js"></script>
<div mfour="testController">Hello</div>

---

To check if the variable is a function just add a check

typeof variableName

It will return the type of variable.

Dude..

If possible, add your function to an object. Like below

var obj = {
    testController: function(){
       alert('123');
    }
};

    $(function() {
        $('[mfour]').each(function(e, t) {
            var a = $(t).attr('mfour');
            console.log($.isFunction(obj[a]));
        })
    });

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