added documentation to conditionals

Author: chuanxshi

general-patterns/conditionals.html

@@ -11,20 +11,106 @@
 */
 
 // NOTE: Paul Irish states that the first statement is only an antipattern when optimizing for 
-// low-bandwidth source (such as for a bookmarklet.
+// low-bandwidth source (such as for a bookmarklet).
 // Using the first statement will generally outperform the regex in a loop, and is faster than the
 // object literal for lower numbers of conditions (they generally even out around 10 conditions).
 // See http://jsperf.com/if-this-or-that
 
-// antipattern
+// Normal Pattern
 if(type==='foo'||type==='bar'){}
 
-// preferred method 1 - regex test
+
+/* alternative method 1 - regex test */
 if(/^(foo|bar)$/.test(type)){}
 
-// preferred method 2 - object literal lookup (smaller if < 5 items)
+
+/* alternative method 2 - object literal lookup (smaller if < 5 items) */
 if(({foo:1,bar:1})[type]){}
 
+
+/* alternative method 3 - binary-search-like approach
+ This approach is best when there are ranges of values for which to test
+*/
+
+if(value==0){
+returnresult0;
+}elseif(value==1){
+returnresult1;
+}elseif(value==2){
+returnresult2;
+}elseif(value==3){
+returnresult3;
+}elseif(value==4){
+returnresult4;
+}elseif(value==5){
+returnresult5;
+}elseif(value==6){
+returnresult6;
+}elseif(value==7){
+returnresult7;
+}elseif(value==8){
+returnresult8;
+}elseif(value==9){
+returnresult9;
+}else{
+returnresult10;
+}
+
+if(value<6){
+if(value<3){
+if(value==0){
+returnresult0;
+}elseif(value==1){
+returnresult1;
+}else{
+returnresult2;
+}
+}else{
+if(value==3){
+returnresult3;
+}elseif(value==4){
+returnresult4;
+}else{
+returnresult5;
+}
+}
+}else{
+if(value<8){
+if(value==6){
+returnresult6;
+}else{
+returnresult7;
+}
+}else{
+if(value==8){
+returnresult8;
+}elseif(value==9){
+returnresult9;
+}else{
+returnresult10;
+}
+}
+}
+
+
+/* alternative method 4 - object/array lookup tables
+ Most useful when there is logical mapping between a single key and a single value
+*/
+
+if(value==0){
+returnresult0;
+}elseif(value==1){
+returnresult1;
+}elseif(value==2){
+returnresult2;
+}
+
+// define the array of results
+varresults=[result0,result1,result2];
+// return the correct result
+returnresults[value];
+
+
 // reference
 // http://paulirish.com/2009/perf/
 </script>