JavaScript problem with promise chaining example - ecmascript-6

Question

I am having a hard time understanding chaining promises in javaScript so I decided to make an example and practice some code this is what I want to do...
Do a "heavy task" for 5 seconds
Do a "medium task" for 3 seconds after heavy task finishes
successfully
If "medium task" is successful to a "small" task of 2 second
The "small task" must display the success message of the heavy task
If "medium task" fails then do an "error task" of 1 second stating
failure reason
while all these are going on do "Some other tasks..."
var p = new Promise(function(resolve, request) {
setTimeout(function() {
console.log("Inside heavy task...");
resolve("Heavy task was a success");
}, 5000);
})
.then(function(value) {
setTimeout(function(value) {
console.log("Inside medium task...");
resolve(value);
//reject("Medium task failed !");
}, 3000);
})
.then(function(value) {
console.log("Inside small task...");
console.log("From small task : " + value);
})
.catch( function(reson){
setTimeout(function(reason){
console.log("Inside error task...");
console.log("Failed due to "+reason);
},1000);
});
console.log("Some other tasks...");
I understand that my code is wrong can someone correct this and explain how this should be done.

Answer 1

Firstly, If you want to pass additional parameters to the callback function of setTimeout then it is done as follows
setTimeout(callback, time, param1, param2, ...)
Now in your code snippet, wrap the second setTimeout function in a promise and return that promise. Also if you want the small task to be asynchronous then wrap it inside a promise also and return that promise.
var p = new Promise(function(resolve, reject) {
setTimeout(function() {
console.log("Inside heavy task...");
resolve("Heavy task was a success");
}, 5000);
})
.then(function(value) {
var p2 = new Promise(function(resolve, reject) {
setTimeout(function() {
console.log("Inside medium task...");
resolve(value);
// reject("Medium task failed !");
}, 3000);
});
return p2;
})
.then(function(value) {
console.log("Inside small task...");
console.log("From small task : " + value);
})
.catch(function(reason) {
setTimeout(function(){
console.log("Inside error task...");
console.log("Failed due to "+ reason);
}, 1000);
});
console.log("Some other tasks...");
I hope this is helpful :)