Problem in removing special characters from a string through js

I am using this function to remove anything other than numbers, but it is giving me error, value.replace in not a f开发者_StackOverflow中文版unction, Here's the function :

function filter_value(value)
{
    var filter = value.replace(/[^0-9.]+/g,''); 
    return filter;
}

If replace is not a function then value is not a string. Make sure you pass a string to the function.

function filter_value(value) {
    return parseInt(value.toString().replace(/\D+/g,''), 10);
}

This will return integer value