JavaScript Multiple Callback Function

callback, javascript

Solution

To accomplish this, you need to pass the next callback into each function.

function printList(callback) {
  // do your printList work
  console.log('printList is done');
  callback();
}

function updateDB(callback) {
  // do your updateDB work
  console.log('updateDB is done');
  callback()
}

function getDistanceWithLatLong(callback) {
  // do your getDistanceWithLatLong work
  console.log('getDistanceWithLatLong is done');
  callback();
}

function runSearchInOrder(callback) {
    getDistanceWithLatLong(function() {
        updateDB(function() {
            printList(callback);
        });
    });
}

runSearchInOrder(function(){console.log('finished')});

This code outputs:

getDistanceWithLatLong is done
updateDB is done
printList is done
finished

Problem

I have been trying to figure out the Callback function feature in Javascript for a while without any success. I probably have the code messed up, however I am not getting any Javascript errors, so I supposed the syntax is somewhat correct. Basically, I am looking for the getDistanceWithLatLong() function to end before the updateDB() begins, and then make sure that ends before the printList() function begins. I have it working with a hardcoded "setTimeout" call on the functions, but I am overcompensating and forcing users to wait longer without a need if the Callback stuff would work. Any suggestions? Below is the code: ``` function runSearchInOrder(callback) { getDistanceWithLatLong(function() { updateDB(function() { printList(callback); }); }); } ```

Original source