[Javascript] - forEach function implementation

forEach.js

function forEach(list, callback, endIndex)
{
    if (!list instanceof Array) console.error('forEach method accepts an instanceof Array as first parameter!')
    
    var end = endIndex || list.length - 1,
        args = [[list, callback, endIndex], Array.prototype.slice.call(arguments, 3)],
        args = args.reduce(function(a,b){ return a.concat(b); });
    
    for(var i = 0; i <= end; i++)
    {
        args.unshift(i);
        callback.apply(list[i], args);
    }
}

// Test
function assert(value, desc)
{
    var result = value ? 'pass' : 'fail';
    console.log(result + ' => ' + desc);
}

var charcuteries = ['rosette', 'coppa', 'mortadelle'];
forEach(
    charcuteries,
    function(index)
    {
        assert(this == charcuteries[index], 'Expected value of ' + charcuteries[index])
    }
)