I am looking to dynamically create methods in JavaScript... In ruby (see below) we have define_method, do we have something similar in JavaScript?
define_method 'name_of_the_method' do
'method code goes in this block'
end
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See answer here stackoverflow.com/questions/3733580/…Matt The Ninja– Matt The Ninja2015-11-16 16:41:15 +00:00Commented Nov 16, 2015 at 16:41
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What is it that you want to do? Like, in JavaScript terms, what are you trying and what exactly do you want the code to do, and why?Pointy– Pointy2015-11-16 16:41:27 +00:00Commented Nov 16, 2015 at 16:41
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To put it another way, what is it about JavaScript function declarations or function expressions that is inadequate for your needs?Pointy– Pointy2015-11-16 16:43:08 +00:00Commented Nov 16, 2015 at 16:43
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I am looking to build a framework around protractor, and want to build a way to handle page objects efficiently... I don't want to have variables that define a path to an element, and individual functions for each element that actually map them... If I can have a function that takes element name + element path I can then use this same function to map my elements and they give me back a function for a given elementPippo– Pippo2015-11-16 16:46:40 +00:00Commented Nov 16, 2015 at 16:46
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how is this a down vote? it's a legit question of someone that never used JS...Pippo– Pippo2015-11-16 16:47:46 +00:00Commented Nov 16, 2015 at 16:47
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1 Answer
Since Javascript treats functions as first-class objects, you can create and assign them at any time. Combined with the Function constructor, the equivalent would be:
function define_method (target, name, code) {
target[name] = new Function(code);
}
This is not super friendly when it comes to taking parameters (it does not have any named params), but will dynamically create a method on the object.
If you want to attach a method to every instance of that type of object, you should use:
target.prototype[name] = new Function(code);
If you have the function ahead of time (no need to dynamically compile it), you can just assign with a dynamic name and existing function:
function define_method(target, name, fn) {
target[name] = fn;
}
Because Javascript treats functions as objects, you can assign them to objects (class prototype or instance) at any time.
