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GBIC >> Source Code >> JavaScript >> Snippet

10 Conditional flow


8 different ways to affect program flow
if .. else ,   switch ,   for ..next,   do .. while ,   while ,   for .. in ,   with ,   ?

if ---------------------------------------------------
if (condition)
  { Block }    //block is one or more lines of code to execute if condition is true

or, more general version :

if (condition)
   { Block }
else
   { Block }



switch ---------------------------------------------
switch (expression)
{
  case "dog" :    //note use of colon at end of line
        { Block }
        break ;   //note use of semicolon at end of line
  case "cat" :
        { Block }
        break ;
  default :
        { Block }
}



for ..next ---------------------------------------------
for (i = 0; i < 10; i ++ //  for (initialize;  condition;  adjust)
  { Block }    //  statements



do .. while ---------------------------------------------
do
  { Block }
while (expression)


while --------------------------------------------------
while (expression)
    { Block }



for .. in ------------------------------------------------
for (myvariable in object)  //cycle through all enumerated properties of the object (elements of Array object)
    { Block }     //order of properites is unknown
     //methods and some properties are not enumerated
Example of for :
for (myvar in wine1)
  { record += 1 }
document.write (record)



with ------------------------------------------------
with (object)
  { Block }    //properties and methods of object can leave off the repetitive portion (shown in parentheses)


? --------------------------------------------------
result = (condition) ? ( if true ) : ( if false ) ;  //conditional operator ?


Additional options -----------------------
 use 'break' to drop out of loop
 use 'continue' to drop out of current iteration of the loop