index.js

/**
 * Run sync loop with async function
 *
 * @example
 * var syncLoop = require('sync-loop');
 * var numberOfLoop = 10;
 * syncLoop(numberOfLoop, function (loop) {
 *  // loop body
 *  var index = loop.iteration(); // index of loop, value from 0 to (numberOfLoop - 1)
 *  doAsyncJob(function(){
 *    // This is callback of your function
 *    loop.next(); // call `loop.next()` for next iteration
 *  })
 *}, function () {
 *  console.log("This is finish function")
 *});
 */
module.exports = function (iterations, process, exit) {
  var index = 0,
    done = false,
    shouldExit = false;

  var loop = {
    next: function () {
      if (done) {
        if (shouldExit && exit) {
          return exit(); // Exit if we're done
        }
      }
      // If we're not finished
      if (index < iterations) {
        index++; // Increment our index
        process(loop); // Run our process, pass in the loop
        // Otherwise we're done
      } else {
        done = true; // Make sure we say we're done
        if (exit) exit(); // Call the callback on exit
      }
    },
    iteration: function () {
      return index - 1; // Return the loop number we're on
    },
    break: function (end) {
      done = true; // End the loop
      shouldExit = end; // Passing end as true means we still call the exit callback
    }
  };
  loop.next();
  return loop;
};