Underscore mixin get object property with default value

_.get.js

//get a key from an object if it exists, otherwise use default
_.mixin({
    get: function(obj, key, default_val){
        if (obj && _.has(obj, key)){
            return obj[key];
        }
        else{
            return default_val != undefined ? default_val : '';
        }
    }
});

updated to make sure obj exists before calling _.has to preview an error when obj is null

updated to check for default_val to not be undefined because it was returning an empty string when default_val was set to false