How to DRY up prototype javascript method definitions?

Question

I'm coming back to "raw" Javascript, and I'm writing classes like this:

var Person;

Person = (function() {

    function Person() {}

    Person.prototype.run = function() {};

    Person.prototype.jump = function() {};

    Person.prototype.talk = function() {};

    return Person;

})();

I feel like the repetition of Person.prototype isn't very DRY: it's also harder to avoid line wrapping. Are there common ways of addressing this? For example, one could assign Person.prototype to a small variable like cls, which would make the lines look more like

cls.run = function() {};

...but that might be too unconventional.

ThiefMaster · Accepted Answer · 2012-06-13 17:39:22Z

4

Since you do not have anything in the prototype you can simply assign a new object to it:

Person.prototype = {
    run: function() {},
    jump: function() {},
    walk: function() {}
};

Otherwise you could use a function such as jQuery's $.extend() to merge two objects:

$.extend(Person.prototype, {
    run: function() {},
    jump: function() {},
    walk: function() {}
});

answered Jun 13, 2012 at 17:39

ThiefMaster

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1 Comment

hvgotcodes Over a year ago

ah i completely forgot about that...+1.

hvgotcodes · Accepted Answer · 2012-06-13 17:38:03Z

2

That's not what DRY really means. Dang it, I have to write 'if' and 'function' a lot too. And I really cant stand 'return' and 'for'. ;)

DRY is for when functionality is copied and pasted, resulting in bloated code and a high maintenance cost. In this case, you are complaining more about the language syntax.

BTW, you are probably ahead of (i.e. more DRY) many people by defining methods on objects.

Having said all that, coffeescript allows you to be less verbose. Way less verbose. Many times you don't need parenthesis or braces, and you don't need prototype at all.

answered Jun 13, 2012 at 17:38

hvgotcodes

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1 Comment

ThiefMaster Over a year ago

Well, repeating Person is kind of ugly - you'd have to change quite a few places in a large object if you ever decided to rename it.

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