I’m juggling between JavaScript and Python (C for only Arduino) and sometimes I cannot wrap my head around the syntaxes, so I decided that it will be a good idea to create a table to refer to when I’m using different languages.

As a refresher,

  • do is an entry loop, which is the condition is evaluated and the loop is started if the condition is true.
  • do-while is an exit loop; the loop is executed at least once, even if the condition never evaluates to true. Until the exit condition is met, the loop runs.

Note here that Python does not have an explicit do-while construct. Therefore we “trick” Python by starting while true, which always evaluates to true and then specify the exit condition.

Loop Python JavaScript
for 
for (start_condition, end_condition, step):
    statements
 
for (start_condition; end_condition; step)
{statements;}
for in array
(elements only)		 
for item in array:
    statements
 
for (let item of array):
{statements;}
for in array
(index and elements)		 
 for index, element in enumerate(array):
    statements
 
 for (let index in array)
{statements array[index];}
for in objects same for any iterable 
for (let index of object)
{statements object[index];}
while 
start_condition
while end_condition:
    statements
    iteration
 
let start_condition;
while(end_condition){
statements;
iteration;}
do while 
while True:
  statements
  iteration
  if (end_condtion):
    break
 
let start_condition;
do{
statements;
iteration;}
while (end_condition)