Object Prototype Function Breaking in jQuery

Question

Someone helped me with a great object prototype for JavaScript but it breaks in jQuery. In jQuery it gives an error:

jquery.min.js:2 Uncaught TypeError: V[g].exec is not a function

I found that the Object.defineProperty block (below) stops the jQuery error. But then it doesn't work. When I call to multiparter() it just returns "undefined". Can anyone help with a solution?

Object.prototype.multiparter = function(route) {
    var newObj = this;
    route.forEach(function(key) {
        newObj = newObj[key]
    });
    return newObj;
};

Object.defineProperty(Object.prototype, 'multiparter',{
    value : function() {},
    enumerable : false
});

var mekBldr = {
    mecha: {
        heads: {
            head01: {
                cost: 0,
                classification: ''
            }
        },
        rightLimbs: {
            legs: {
                rightleg01: {
                    cost: 0,
                    classification: ''
                }
            }
        },
        leftLimbs: {
            legs: {
                leftleg01: {
                    cost: 0,
                    classification: ''
                }
            }
        }
    }
};
var part = 'heads';
var stuck2 = [part];
var part1 = 'leftLimbs';
var part2 = 'legs';
var stuck = [part1, part2];
mekBldr.mecha.multiparter(stuck2).head01.cost = 2;
//goal: mekBldr.mecha.leftLimbs.legs.leftleg01.cost = 5;
mekBldr.mecha.multiparter(stuck).leftleg01.cost = 5;

Community · Accepted Answer · 2017-05-23 10:32:29Z

1

By passing a value to the descriptor, you've just overwritten the method with that empty function (which is the one doing nothing and returning undefined). If you really want to define a method on Object.prototype (which you absolutely should not do), you'd need to use

Object.defineProperty(Object.prototype, 'multiparter', {
    value: function(route) {
        return route.reduce(function(newObj, key) {
            return newObj[key]
        }, this);
    },
    enumerable: false,
    configurable: true
});

edited May 23, 2017 at 10:32

CommunityBot

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answered Oct 20, 2016 at 17:06

Bergi

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4 Comments

Tachyon80 Over a year ago

Thanks for the info. It sounds like I shouldn't solve my problem by using Object.prototype. What is a better solution? Towards the bottom of my code sample above, you can see "goal". That's what I'm trying to accomplish. Any help would be greatly appreciated.

Bergi Over a year ago

Make it a static function: multiparter(mekBldr.mecha, stuck2).head01.cost not a method. One day you'd encounter an object that had its own multiparter property, and your code would break.

Tachyon80 Over a year ago

Like this? codefunction multiparter(theObj,route) { route.forEach(function (key) { theObj = theObj[key] }); return theObj; }code

Bergi Over a year ago

@user1592980 Yes, exactly. Though I recommend to use reduce instead of forEach like in my answer :-)

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