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    2.1.1 • Public • Published


    Maintainable code for Slack interactive messages, modals, and home tabs.

    Lightweight, zero-dependency library for declaratively building Slack Block Kit UI.

    View the Docs »

    Quick Start Guide · Request Feature · Report Bug

    An example of using Block Builder

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    🎉 Block Builder Version 2.0 is here! Learn about the new features and how to install it here.

    Block Builder helps you keep your Slack app code for UI maintainable, testable, and reusable. It has a declarative, chainable syntax inspired by SwiftUI and is built for better UI architecture.


    • Declarative SwiftUI inspired syntax.
    • The ability to build more complex flows using loops and conditionals.
    • A printPreviewURL() method that outputs a link to preview your UI on Slack's Block Kit Builder website for easier prototyping.
    • A set of helper functions for formatting text with Slack's markdown standard.
    • In-depth doc site at
    • Support for all current Slack Block Kit objects.
    • A great TypeScript experience.
    • Extensive JSDoc hints with explanations, validation rules, and quick links to full documentation.
    • Zero dependencies.

    🚀   Coming Soon

    • Paginator component.
    • Accordion component.

    🎁   Benefits

    • Write three times less code.
    • Build more sophistocated, elegant flows.
    • Design better UI architecture for your Slack apps.
    • Focus more on code in your IDE than on studying the Slack API docs.
    • Easily integrate localizations into your app.

    ☎️   Let's Talk?

    Feedback – love it! Aside from GitHub Issues, there are Slack channels available in popular bot communities to discuss Block Builder – we'll see you there! 🙌

    💾   Installation

    Block Builder requires Node.js 12 or higher, and, when using TypeScript, TypeScript 3.8 or higher.

    Using NPM:

    npm install --save slack-block-builder

    Using Yarn:

    yarn add slack-block-builder

    👾   Usage

    For full documentation, make sure you head over to


    The functions for creating objects can be both imported directly or through an object that groups them by category.

    // Importing exposed groups of objects
    import { Surfaces, Blocks, Elements, Bits, Utilities } from 'slack-block-builder';
    // Importing objects top-level
    import { Modal, Section, Actions, Button } from 'slack-block-builder';

    The same goes for importing Slack markdown helper functions:

    // Importing the Md object
    import { Surfaces, Blocks, Md } from 'slack-block-builder';
    // Importing the functions top-level
    import { Modal, Section, bold, link } from 'slack-block-builder';

    Group Explanations

    Surfaces – Contains functions for creating modals, messages, home tabs, and workflow steps.

    Blocks – Layout blocks used to organize the UI.

    Elements – UI elements that are used to capture user interaction.

    Bits – These are composition objects and other bits and pieces from Slack's docs. Included are Attachment, Options, OptionGroup, and ConfirmationDialog. They felt like they were deserving of their own category.

    Utilities – A group of utility functions. See Utility Functions.

    Md – Helper functions for formatting text with Slack's markdown. See Markdown Helpers.

    Block Kit Support and Reference

    Below is a list of supported objects and how to access them in Block Builder:

    Name Type Support Accessed Via
    Home Tab Surface Surfaces.HomeTab()
    Message Surface Surfaces.Message()
    Modal Surface Surfaces.Modal()
    Workflow Step Surface Surfaces.WorkflowStep()
    Actions Block Blocks.Actions()
    Context Block Blocks.Context()
    Divider Block Blocks.Divider()
    File Block Blocks.File()
    Header Block Blocks.Header()
    Image Block Blocks.Image()
    Input Block Blocks.Input()
    Section Block Blocks.Section()
    Button Element ✅️ Elements.Button()
    Checkboxes Element Elements.Checkboxes()
    Date Picker Element Elements.DatePicker()
    Time Picker Element Elements.TimePicker()
    Image Element Elements.Img()
    Overflow Menu Element Elements.OverflowMenu()
    Radio Buttons Element Elements.RadioButtons()
    Plain-Text Input Element Elements.TextInput()
    Select Menus Element Elements.[Type]Select()
    Multi-Select Menus Element Elements.[Type]MultiSelect()
    Option Composition Object Bits.Option()
    Confirm Dialog Composition Object Bits.ConfirmationDialog()
    Option Group Composition Object Bits.OptionGroup()
    Attachment Legacy Feature Bits.Attachment()

    Creating a Simple Interactive Message

    Let's take a look at how to compose an interactive message. Even though Slack now has modals, these have always been the basis for Slack apps.

    Functions that return Block Kit objects have setter methods for all of the properties, but also support parameters that are passed into the constructor for properties with primitive types.

    import { Message, Blocks, Elements } from 'slack-block-builder';
    const myMessage = ({ channel, dangerLevel }) => {
      return Message()
        .text('Alas, my friend.')
            .text('One does not simply walk into Slack and click a button.'),
            .text('At least that\'s what my friend Slackomir said :crossed_swords:'),
                .text('Sure One Does')
                .danger(dangerLevel > 42), // Optional argument, defaults to 'true'
                .text('One Does Not')

    And now an example with using both the setter methods and passing parameters into the functions at initiation:

    import { Message, Blocks, Elements } from 'slack-block-builder';
    const myShorterMessage = ({ channel, dangerLevel }) => {
      return Message({ channel, text: 'Alas, my friend.' })
          Blocks.Section({ text: 'One does not simply walk into Slack and click a button.' }),
          Blocks.Section({ text: 'At least that\'s what my friend Slackomir said :crossed_swords:' }),
              Elements.Button({ text: 'Sure One Does', actionId: 'gotClicked' })
                .danger(dangerLevel > 42), // Optional argument, defaults to 'true'
              Elements.Button({ text: 'One Does Not', actionId: 'scaredyCat' })

    Both of these examples render the message below. And the best part? It only took 15 lines of code, as opposed to the 44 lines of JSON generated as a result.

    An example of using Block Builder for Messages

    View Example on Slack Block Kit Builder Website

    Creating a Simple Modal

    Let's take a look at how modals are created. Here we'll also take a look at working with Bits and with loops, by adding options with the method.

    You'll noticed that we've added an inline condition that returns an initial option only if one has been passed into the function. This is because all the setter methods prune values of undefined, uncovering opportunities for inline logic.

    import { Modal, Blocks, Elements, Bits } from 'slack-block-builder';
    const myShorterModal = ({ menuOptions, selected }) => {
      return Modal({ title: 'PizzaMate', submit: 'Get Fed' })
          Blocks.Section({ text: 'Hey there, colleague!' }),
          Blocks.Section({ text: 'Hurray for corporate pizza! Let\'s get you fed and happy :pizza:' }),
          Blocks.Input({ label: 'What can we call you?' })
              Elements.TextInput({ placeholder: 'Hi, my name is... (What?!) (Who?!)' })
          Blocks.Input({ label: 'Which floor are you on?' })
              Elements.TextInput({ placeholder: 'HQ – Fifth Floor' })
          Blocks.Input({ label: 'What\'ll you have?' })
              Elements.StaticSelect({ placeholder: 'Choose your favorite...' })
                  .map((item) => Bits.Option({ text:, value: })))
                .initialOption(selected && Bits.Option({ text:, value: }))))

    Both of these examples render the modal below.

    An example of using Block Builder for Modals

    View Example on Slack Block Kit Builder Website

    Utility Functions

    The Utilities object contains various utility functions for creating UI. Currently, there are two:

    BlockCollection() – Accepts multiple arguments or an array of blocks and returns them in an array, in their built state.

    AttachmentCollection() – Accepts multiple arguments or an array of attachments and returns them in an array, in their built state.

    These two functions are useful when you wish to keep surface or view configuration separate from UI representation.

    An example using Slack's WebClient from their SDK for Node.js:

    import { BlockCollection, AttachmentCollection, Blocks } from 'slack-block-builder';
    import { WebClient } from '@slack/web-api';
    const client = new WebClient(process.env.SLACK_TOKEN);{
      channel: 'ABCDEFG',
      text: 'Hello, my dear, sweet world!',
      blocks: BlockCollection( /* Pass in blocks */ ),
      attachments: AttachmentCollection( /* Pass in attachments */ ),
    .then((response) => console.log(response))
    .catch((error) => console.log(error));

    Another example where you might find BlockCollection() helpful is when unfurling links in messages:

    import { BlockCollection, Blocks } from 'slack-block-builder';
    import { WebClient } from '@slack/web-api';
    const client = new WebClient(process.env.SLACK_TOKEN);
    const unfurl = ({ channel, ts, url }) =>{
      unfurls: { [url]: BlockCollection( /* Pass in blocks */ ) },
    .then((response) => console.log(response))
    .catch((error) => console.log(error));

    Markdown Helpers

    Often you'll find that you need to format text in your messages and modals. Block Builder has helper functions available to simply that process. They are available both as members of the Md object and as top-level imports. You can find the full list of functions on the Block Builder doc site:

    import { Message, Blocks, Md } from 'slack-block-builder';
    const myMdMessage = ({ channel, user }) => {
      const slashCommands = ['/schedule', '/cancel', '/remind', '/help'];
      return Message({ channel, text: 'Alas, my friend.' })
          Blocks.Section({ text: `:wave: Hi there, ${Md.user(user)}!` }),
          Blocks.Section({ text: `${Md.italic('Sorry')}, I didn't get that. Why don't you try out some of my slash commands?` }),
          Blocks.Section({ text: `Here are some of the things that I can do:` }),
              .map((item) => Md.codeInline(item)))))

    View Example on Slack Block Kit Builder Website

    🔗   Other Useful Slack-Related Projects

    Bolt for JavaScript – A simple framework for building Slack apps, developed by Slack themselves.

    Node Slack SDK – A great and powerful SDK for building Slack Apps from the ground up.

    🔥   Acknowledgements

    @korywka Taras Neporozhniy (@korywka) - For help and ideas along the way!

    @ft502 Alexey Chernyshov (@ft502 on Dribbble) - For such a beautiful logo!

    @slackhq SlackHQ (@slackhq) - For such a wonderful product and API!

    ✒️   Author

    @raycharius Ray East (@raycharius) - Huge Fan of Slack and Block Builder Maintainer


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