My advanced version of playsound macro. Testers and comments are welcome

Comments

• TheMadExile

  February 2016

  I suppose users of the Twine 1 vanilla story formats might like this.
  
  As a suggestion, in your InArray function, don't use the for…in loop to iterate arrays. Use a standard for loop, with the 3-part syntax, to iterate arrays. For example:

  function InArray(array, value) {
  	for (var i = 0, len = array.length; i < len; ++i) {
  		if (array[i] == value) {
  			return true;
  		}
  	}
  
  	return false; 
  }
  

  
  Reasoning:
  Arrays in JavaScript are just objects (i.e. Array object) with some extra syntactical sugar added. What the for…in loop does is iterate over all of an object's enumerable properties (in arbitrary order). The basic enumerable properties on an array object are its indices, which is why using the for…in loop works at all. However, the for…in loop does not limit itself to the object's own properties and will iterate all enumerable properties from the property chain as well. You really do not want, or need, to be traversing an array's property chain just to iterate over its indices.
  
  Now, you could guard against enumerable properties on the property chain by using the hasOwnProperty() method to ensure that an iterated property is actually one of the array's own, however, that's extra work your loop, generally, doesn't need to be doing.
  
• yun

  February 2016 edited February 2016

  I knew that JS arrays are not regular arrays and, e.g, array[0] and array[2] may exist while array[1] may absent, that's why for...in is used. But if it scans unnecessary properties, you are probably right. Why are you using an extra variable "len" instead of for (var i=0; i<array.length; ++i), however?
  Meanwhile, I changed the code and added domacro method to allow all those macros to be called as a function in Twine this way:

  <<set $soundmacro=
  function(macro,paramstr)
  {macros[macro].domacro(macro, paramstr);}
  >>
  <<set $chimes=
  function(n)
  {state.history[0].variables["soundmacro"]("loopsound",'"1bell.wav" '+n);}
  >>
  <<set $chimes(12)>>
  
• greyelf

  February 2016

  yun wrote: »

  Why are you using an extra variable "len" instead of for (var i=0; i<array.length; ++i), however?

  Local variables are generally faster to access than object properties and the value of array.length needs to be determined for each looping.
  
  
• yun

  February 2016

  BTW, how to call this InArray() function from Twine? (Sugarcane again).
  I am trying the following and get a ReferenceError: InArray is not defined)

  <<set $chimes=
  function(n)
  {macros["playsound"].soundtracks["1bell"].volume=InArray(state.history[0].passage.tags,"salon")?1:0.5;
   $soundmacro("loopsound",'"1bell.wav" '+n);}
  >>
  

  (Everything else works.)
• TheMadExile

  February 2016

  As a bit of a preface to my reply. Ideally, you should be using one of the standard library Array methods to do this, rather than hand-rolling your own search function. However, since the macro set and story formats you're dealing with support IE8 (sans polyfills), you're kind of hosed in that regard.
  
  

  yun wrote: »

  I knew that JS arrays are not regular arrays and, e.g, array[0] and array[2] may exist while array[1] may absent, that's why for...in is used. But if it scans unnecessary properties, you are probably right.

  The concept you're thinking of is known as a sparse array.
  
  You are unlikely to see a sparse array come out of the vanilla story formats (or most anything, really), so unless you know for a fact that you'll be dealing with them it's, generally, best to assume that any array you interact with will not be sparse.
  
  In later versions of the ECMAScript (JavaScript) standards, there are several more ways to deal with arrays, many of which handle sparse arrays better than for…in allows.
  
  

  yun wrote: »

  Why are you using an extra variable "len" instead of for (var i=0; i<array.length; ++i), however?

  So you aren't having to lookup the length property within the array stored within the array variable every time the loop conditional is checked. Caching the value is just a bit of a micro optimization.
  
  Normally, you shouldn't worry too much about accessing object properties—just go ahead do it. However, in situations where you're going to be reusing the same property value over and over again (e.g. within a loop), then, as long as the property isn't going to mutate on you, you may want to consider caching it to speed up access.
  
  Since InArray() iterates arrays, which are not being mutated, to search for a particular value, then caching the length of the array isn't a bad idea.
  
• yun

  February 2016

  I thought there should be a standard method for checking if a value is in array, but brief googling showed that people use functions like my InArray. And of course I want as much cross-browser compatibility as possible.
  I thought accessing a property (not a method calculating something) and a single variable doesn't differ much. But even if it does, how many tags may a passage have? Usually no more than a couple. Saving several nanoseconds while looping them it not worth
  
  Again, how to call InArray() defined in my script passage from Twine code? It says "InArray is not defined", see an example above.
• greyelf

  February 2016

  yun wrote: »

  I thought there should be a standard method for checking if a value is in array...

  Did you look at the indexOf() method, or does than not do what you want?

  if (array.indexOf(value) != -1) {
  ... found the value in the array ...
  }
  

  yun wrote: »

  Again, how to call InArray() defined in my script passage from Twine code? It says "InArray is not defined", see an example above.

  Your issue is one of Scope, your InArray() function is declared in one local scope (a script tagged passage) and you are trying to use it in a different local scope (within an anonymous function) which is why you get the error message.
  
  You would have to make your InArray() function global for it to be seen everywhere, one common method used to do this is to define the function on the global window object although you could use the above indexOf() function instead which is already available on any array.
  
  The following is a copy of your InArray function defined on the window object.

  if (! window.InArray) {
  	window.InArray = function(array, value) {
  		for (var i=0; i<array.length; ++i) {
  			if(array[i]==value) return true;
  		}
  		return false;
  	};
  }
  
• TheMadExile

  February 2016 edited February 2016

  yun wrote: »

  I thought there should be a standard method for checking if a value is in array, but brief googling showed that people use functions like my InArray. And of course I want as much cross-browser compatibility as possible.

  Doing a brief search did you no favors here. greyelf has already linked <Array>.indexOf() and a future version (ES7) will add <Array>.includes().
  
  As I noted above, the Twine 1 vanilla story formats don't include any polyfills, however, so you probably shouldn't use <Array>.indexOf() and are better off sticking with your custom InArray() function.
  
  

  greyelf wrote: »

  Did you look at the indexOf() method, or does than not do what you want?

  if (array.indexOf(value) != -1) {
  ... found the value in the array ...
  }
  

  It does exactly what yun needs. However, <Array>.indexOf() doesn't exist in some of the older browsers supported by the Twine 1 vanilla story formats and the original version of these macros. If yun is trying to maintain compatibility, then using <Array>.indexOf() is a non-starter, unless they also include a polyfill for it.
  
  Speaking personally, I would go ahead and add a polyfill, so I could use the standard library method. However, I'm getting the impression that yun wouldn't be in favor of that.
  
• greyelf

  February 2016

  TheMadExile wrote: »

  However, <Array>.indexOf() doesn't exist in some of the older browsers ....

  I did not include that information in my previous comment because it is available in the linked page, which also includes a polyfill to support those older browsers.
  
• yun

  February 2016

  Someone wrote that indexOf() was only for strings and I believed without checking Now I see it works even with my rather old browsers. IE8, however, does not support Audio, so I will not bother taking care about it at all. Normal people don't use it anyway
  Thanks to both of you!