Is using Prototype to extend native objects bad? [closed]

Question

I read somewhere that using prototype to extend native objects (String, Number, Array, etc.) was a bad idea. Is this true? Why or why not?

Answer 1

I don't think it's bad. If you have a look at Ruby on Rails, very many native objects are extended with custom functionality and it's a very good framework.

What would be bad is if you change existing methods on native objects. this could cause unforseen consequences.

Answer 2

There's a great discussion about this in this video from JSConf 2011 by Andrew Dupont. http://blip.tv/jsconf/jsconf2011-andrew-dupont-everything-is-permitted-extending-built-ins-5211542

Basically the points are:

• Don't extend Object.prototype
• Some people might like to extend things, some people don't
• You need to know what you're doing
• Don't use two libraries that extend things, because it can be bad
• Extending prototypes to add standard functionality is almost always ok.