Serializing a collection of JavaScript promises for execution

Question

Serializing a collection of JavaScript promises for execution

What is the best method for serializing a group of promised function calls?

var promised_functions = [
 fn1,  // execute this function
 fn2,  // once the previous resolves, call this one
 fn3   // once the previous resolves, call this one
];
q.serialize_functions(promised_functions)
.then(function(){
 // if all promises resolve, perform some action
})

javascript promise q

Answer 1

Answer №1

If you're looking for the answer, check out the details in the official documentation:

promised_functions.reduce(Q.when, Q()).then(function () {
    // Execute certain actions if all promises are resolved
});

Scroll down to the "Sequences" part of the documentation. To directly copy it:

In case you have multiple promise-producing functions that need to be executed one after another, you can do it manually:

return foo(initialVal).then(bar).then(baz).then(qux);

But, if you wish to run a dynamically created sequence of functions, this is what you need:

var funcs = [foo, bar, baz, qux];

var result = Q(initialVal);
funcs.forEach(function (f) {
    result = result.then(f);
});
return result;

You can simplify this using reduce:

return funcs.reduce(function (soFar, f) {
    return soFar.then(f);
}, Q(initialVal));

Alternatively, you could opt for the concise version:

return funcs.reduce(Q.when, Q());

That's the information straight from the source.

Answer 2

If you're looking for the answer, check out the details in the official documentation:

promised_functions.reduce(Q.when, Q()).then(function () {
    // Execute certain actions if all promises are resolved
});

Scroll down to the "Sequences" part of the documentation. To directly copy it:

In case you have multiple promise-producing functions that need to be executed one after another, you can do it manually:

return foo(initialVal).then(bar).then(baz).then(qux);

But, if you wish to run a dynamically created sequence of functions, this is what you need:

var funcs = [foo, bar, baz, qux];

var result = Q(initialVal);
funcs.forEach(function (f) {
    result = result.then(f);
});
return result;

You can simplify this using reduce:

return funcs.reduce(function (soFar, f) {
    return soFar.then(f);
}, Q(initialVal));

Alternatively, you could opt for the concise version:

return funcs.reduce(Q.when, Q());

That's the information straight from the source.

Answer 3

Answer №2

Every now and then, the for loop can actually be quite useful.

for(const func of asynchronousFunctions) {
  await func()
}

Answer 4

Every now and then, the for loop can actually be quite useful.

for(const func of asynchronousFunctions) {
  await func()
}

Serializing a collection of JavaScript promises for execution

Answer №1

Answer №2

Similar questions

Configuring v-model with dynamic attribute in Vue.js

Ways to resolve the error message "TypeError: 'setOption' is not a function on type 'MutableRefObject' in React"

How to Retrieve the Absolute Index of the Parent Column Using jQuery Datatables

I am looking to retrieve data from the Graph API JSON and gradually refine my search to achieve successful

Switching the navbar state from a regular mode to a collapsed mode can be done manually

What could be causing my completed torrents to sometimes not be saved to my disk?

Error occurred during download or resource does not meet image format requirements

Using a jQuery function to search for values in an array

Is it possible to capture a Browser TAB click event using JavaScript or AngularJS?

A more effective method for restricting the properties of a field in an aggregate query

Encountering an error message stating, "Unable to assign value to 'onclick' property"

Error: Unrecognized error encountered while using Angularjs/Ionic: Property 'then' cannot be read as it is undefined

Guide on implementing iterative data path in v-for loop using Vue

Difficulty in displaying additional search outcomes

Error encountered when utilizing sceneLoader to import a scene produced by the THREE.js Editor

Reducing the size of textures in three.js

The initial JavaScript load shared by all users is quite large in the next.js framework

Utilizing Material-UI List components within a Card component triggers all onClick events when the main expand function is activated

Obtaining zip files using AngularJS

Best practices for working with HTML elements using JavaScript