constructor.name is undefined in Internet Explorer

Question

My debugging work in IE ended today by finding that constructor.name is undefined.

I created the following simple code that reproduces the issue:

({}).constructor.name === undefined // => true

Is there any workaround to make this work?

Maybe overriding somehow the prototype?

If possible, I don't want to change the syntax, because the change would be major.

JSFIDDLE

Answer 1

From matt.scharley.me

/**
 * Hack in support for Function.name for browsers that don't support it.
 * IE, I'm looking at you.
**/
if (Function.prototype.name === undefined && Object.defineProperty !== undefined) {
    Object.defineProperty(Function.prototype, 'name', {
        get: function() {
            var funcNameRegex = /function\s([^(]{1,})\(/;
            var results = (funcNameRegex).exec((this).toString());
            return (results && results.length > 1) ? results[1].trim() : "";
        },
        set: function(value) {}
    });
}

Answer 2

The problem is simply that the name property of function objects is not supported in Internet Explorer. The property is non-standard (up until ECMAScript 6, at least) so it's not altogether surprising.

There isn't a completely reliable workaround so I would suggest trying to do without it if possible. However, you may be able to extract the name from the string representation of the function. Here a couple of links that deal with this that I got from a quick search:

• Javascript get Function Name?
• https://gist.github.com/dfkaye/6384439

Update

From the comments, it turns out that the goal of the question author is to test whether a variable is a reference to a plain object create by the Object constructor. A reliable way of doing this for a variable a is

Object.prototype.toString.call(a) == "[object Object]"

For more information I recommend the following page written by Angus Croll:

http://javascriptweblog.wordpress.com/2011/08/08/fixing-the-javascript-typeof-operator/