A better typeof for JavaScript, with tests cases

betterTypeOf.js

/**
 * @see http://javascriptweblog.wordpress.com/2011/08/08/fixing-the-javascript-typeof-operator/
 */
function betterTypeOf(input) {
    try {
        return Object.prototype.toString.call(input).match(/^\[object\s(.*)\]$/)[1].toLowerCase();
    } catch (e) {
        return typeof input;
    }
}

function Plop() {
    this.foo = 2;
    return {
        do: function() {
            return 42;
        }
    }
}

cases = [
    -1,
    0,
    2,
    2.2,
    [1, 2],
    {a: 1},
    null,
    undefined,
    NaN,
    Plop,
    Plop(),
    new Plop()
];

cases.forEach(function(testCase) {
    console.log(testCase, typeof testCase, betterTypeOf(testCase));
});

output.txt

-1 'number' 'number'
0 'number' 'number'
2 'number' 'number'
2.2 'number' 'number'
[ 1, 2 ] 'object' 'array'
{ a: 1 } 'object' 'object'
null 'object' 'null'
undefined 'undefined' 'undefined'
NaN 'number' 'number'
[Function: Plop] 'function' 'function'
{ do: [Function] } 'object' 'object'
{ do: [Function] } 'object' 'object'

Not sure if this works for uninstantiated variables..

betterTypeOf(xxx) // ReferenceError: xxx is not defined

Edit: This is mentioned in the original article as a limitation of using a function in place of the native typeof.