training.shoppinpal.com
  • Introduction
  • 1. The Ideal Workspace
    • The Perfect Machine
      • For Biz Team
      • For Developers
      • For Designers
    • Setup a machine in the cloud
      • Solution
      • Setup box on Azure
        • Create a machine on Azure
        • Test drive your remote machine
        • Setup Dropbox On Azure
      • Setup box on DigitalOcean
        • Setup UI
        • Shared FileSystem
          • Dropbox
            • Use locally developed node modules in another project
          • sshfs
        • Long Running Sessions
      • Feedback
  • 2. Learning Git
    • Static Code Analysis
  • 3. The Backend
    • Use Containers
    • Setup a loopback project
    • Lockdown
    • Build a better mousetrap
    • The abyss stares back
    • Built-in models
    • Extending built-in models
    • Understanding UserModel
    • Boot Scripts
    • Promises
    • Find roles for current user
    • Loopback Console
    • Current User
  • 4. Multi-tenancy With Loopback
    • What is Multi-Tenancy
    • Architecting with Loopback
    • Define scope for Roles
    • Role Resolvers
    • Access Control For Tenants
    • Better Programming with multi-tenancy
  • 5. The Frontend
    • The Browser
    • Unit Testing
      • Motivation behind this blog
      • How to write a test
      • Karma and Jasmin
      • Writing Tests
    • End-2-End Testing
    • Angular 1.x
    • Angular 2
      • Testing
  • 6. ElasticSearch
    • Better Search with NGram
    • NGram with Elasticsearch
    • Fun with Path Hierarchy Tokenizer
    • Working with Mappings and Analyzers
  • 7. Promises
    • What are Promises
    • Promise Implementations
    • Nuances
    • What should we use
  • 8. Learning Docker
    • Docker Swarm
  • 9. Queues & Workers
    • PHP workers in AWS EBS
    • NodeJS workers in AWS EBS
      • SQS Daemon by AWS
      • SQS Daemon in NodeJS
      • SQS polling by worker
    • Gearman
  • 10. Docker
    • Capabilities
  • Appendix
    • Bug in WebStorm deployments
    • The Perfect Terminal
    • Scalable App Deployment with AWS
    • Chrome Tips & Tricks
    • Host your own Gitbook
    • Gitbook Tips & Tricks
    • How to handle support incidents
    • Dev Resources
    • Debug e2e Tests on CircleCI
    • Logging
    • Authentication Principles
    • Mac
    • nvm
    • Unify testing with npm
      • Debugging Mocha
    • Sequence Diagrams
    • Project Sync via IDE
      • SFTP with WebStorm
      • SFTP with Visual Studio
    • Soft Linking
    • NodeJS Profiling
      • How to find node.js performance optimization killers
    • Setup Packer on Azure
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  1. 7. Promises

What are Promises

Previous7. PromisesNextPromise Implementations

Last updated 7 years ago

The absolute reference:

  1. Promises are nothing but a chain of success/fail events

  2. We can use promises in nested callback which are dependent to each other this is termed as a callback hell It is hard to understand and creates lot of confusion.

  3. Promises can handle global errors.

  4. Promises can be chained (you don't have this encapsulation like callbacks)

  5. Promise is an interface class that helps you to control if the call to a function - that may be executed asynchronously - has finished successfully or with an error. It is very similar to have a try-catch-finally block for async calls.

https://www.promisejs.org/