loops.js

.then(() => {
  var i = 0;
  const whileHeapList = () => {
    i++;
    if (i < 5) {
      // artifically delayed call 
      log.asyncCall().then(log => {
        if (log) {
          // first inner loop
          const firstInnerLoop = () => {
            if (j < 5) {
              j++;
              // continue iterating loop
              firstInnerLoop();
            }
          }
        } else {
          // 2nd inner loop
          const secondInnerLoop = () => {
            log2.asyncCal().then(log => {
              if (log) {
                // continue iterating current log
                asyncMSG();
              } else {
                // break out of current loop and iterate OUTTER loop
                whileHeapList();
              }
            });
          }
        }
      })
      // continue iterating CURRENT loop --> whileHeapList
      whileHeapList();
    }
  };
  return new Promise(whileHeapList);
})