tracker issue : CF-4205052

Issue: The docs for the various array looping constructs should link to a central doc which outlines how they handle sparse arrays.

Repro:

<cfset myArray = ["foo",javaCast("null","")]>
<cfset myArray[4] = "bar">

<!--- These loop 2 times --->
<cfset i = 0>
<cfloop array="#myArray#" index="myElement">
  <cfoutput>#++i#</cfoutput>
</cfloop>
<hr>
<cfscript>
  i = 0;
  cfloop(array=myArray, index="myElement") {
	  writeOutput(++i);
  }
  writeOutput("<hr>");
  i = 0;
  for(myElement in myArray) {
	  writeOutput(++i);
  }
  writeOutput("<hr>");
</cfscript>

<!--- These loop 4 times --->
<cfloop from="1" to="#myArray.len()#" index="i">
  <cfoutput>#i#</cfoutput>
</cfloop>
<hr>
<cfscript>
  cfloop(from=1, to=myArray.len(), index="i") {
	  writeOutput(i);
  }
  writeOutput("<hr>");
  myArray.each(function(myElement, myIndex, myArray) {
	  writeOutput(myIndex);
  });
  writeOutput("<hr>");
  myArray.map(function(myElement, myIndex, myArray) {
	  writeOutput(myIndex);
  });
  writeOutput("<hr>");
  myArray.filter(function(myElement, myIndex, myArray) {
	  writeOutput(myIndex);
	  return true;
  });
  writeOutput("<hr>");
  myArray.reduce(function(myResult, myElement, myIndex, myArray) {
	  writeOutput(myIndex);
  });
  writeOutput("<hr>");
</cfscript>

Related ticket: CF-3864256

Related URL: https://www.bennadel.com/blog/3531-coldfusion-2016-skips-over-undefined-elements-with-for-in-array-loop.htm

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