Loops and Iterations Loops are used to run a block of code multiple times until a condition is met. Both Python and JavaScript support , , and loops. Python also has the unique construct. Comparison Table Concept JavaScript Example Python Example -------------------- ---------------------------------------------- --------------------------------------- For loop While loop Do-while loop Not available in Python For-in loop For-of loop Break statement Continue statement For-else Not available in JavaScript For loop The loop is used when we know how many times we want to repeat something. Example, Printing even numbers 0–10 JavaScript Python Equivalent While Loop Used when we don’t know in advance how many times the loop will run. Example, Login attempts JavaScript Python Equivalent Do-While Loop (JS only) JavaScript supports do-while, which runs the loop at least once before checking condition. Python does not have direct do-while. It can be simulated with while True + break. Example, User input until correct password JavaScript Python Equivalent Break and Continue Both languages use them similarly. Break Ends the loop immediately. JavaScript Python Equivalent Continue Skips current iteration and continues to next. JavaScript Python Equivalent Nested Loops Loops inside loops, often used for matrices or patterns. JavaScript Python Equivalent Iterating Over Collections JS splits object and array iteration. Python uses for-in for both. JavaScript Python Equivalent For-else (Python only) Runs else block if loop finishes normally (no break). Useful for search tasks. Example Searching item in list Python Javascript Equivalent Summary For loop: Known iterations. While loop: Unknown iterations until condition fails. Do-while (JS only): Runs at least once. Break: Exits loop early. Continue: Skips iteration. Nested loops: Useful for multidimensional problems. Both JS and Python support loops with collection iteration. ✅ Loops are one of the most important control flow concepts. They allow repetitive tasks like iterating over arrays, handling input, or building dynamic programs.