barrel-js

barrel-js is a simple & minimal npm package to build semantic templates for JSON objects and strings.

Install

NPM

npm install barrel-js

Yarn

yarn add barrel-js

Getting started

compile()

JSON templates

barrel-js templates look like regular JSON objects, with embedded template expressions.

{
    "title": "Welcome",
    "body": "Hey ${first_name}! Great to have you here."
}

A template expression is wrapped into ${ + key + } symbols.

You can compile this templates in JavaScript by using the compile function, which takes two parameters

1. the JSON or String template
2. a context object of template keys and their corresponding values

Example

To receive the parsed template with its given context, execute the compile function:

const barrel = require('barrel-js');

let template = {
    "title": "Welcome",
    "body": "Hey ${first_name}! Great to have you here."
};

let context = {
    "first_name": "David"
};

let payload = barrel.compile(template, context);

This will result in following JSON object

{
    "title": "Welcome",
    "body": "Hey David! Great to have you here."
}

Escaping template expressions

Template expressions can be escaped by using \\ in front of the expression and the closing } symbol. For example "Hey \\${first_name\\}!" will result in "Hey ${first_name}!".

filter()

Filtering JSON properties

To filter a json payload for specific properties use the filter function.

const barrel = require('barrel-js');

let template = {
    "type": "section",
    "text": {
        "type": "plain_text",
        "text": "This is a section block."
    },
    "accessory": {
        "type": "button",
        "text": {
            "type": "plain_text",
            "text": "Button",
            "emoji": true
        },
        "value": "click_me_123"
    }
};

let result = barrel.filter(payload.get_object, "text")

This will result in following JSON object

[ 
   { 
      "type":"mrkdwn",
      "text":"This is a section block."
   },
   "This is a section block.",
   { 
      "type":"plain_text",
      "text":"This is a section block."
   },
   "This is a section block."
]

Use an optional maximum property to reduce the number of returned items.

barrel.filter(payload.get_array, "text", 1);

This will throw an index out of range error if the number of found items is lower than the provided max items property.

contains()

checking for JSON sub-structures

To check if a specific json structure exists in this payload use the contains function.

const barrel = require('barrel-js');

let template = {
    "type": "section",
    "text": {
        "type": "plain_text",
        "text": "This is a section block."
    },
    "accessory": {
        "type": "button",
        "text": {
            "type": "plain_text",
            "text": "Button",
            "emoji": true
        },
        "value": "click_me_123"
    }
};

let result = barrel.contains(template, { "type": "section" });

This will return either true or false.

match()

filtering for JSON sub-structures

To filter a JSON object or array for a specific json sub-structure use the match function.

const barrel = require('barrel-js');

let template = {
    "type": "section",
    "text": {
        "type": "plain_text",
        "text": "This is a section block."
    },
    "accessory": {
        "type": "button",
        "text": {
            "type": "plain_text",
            "text": "Button",
            "emoji": true
        },
        "value": true
    }
};

let result = barrel.match(template, { "type": "button", "value": true });

This will result in following JSON object

[ 
   {
        "type": "button",
        "text": {
            "type": "plain_text",
            "text": "Button",
            "emoji": true
        },
        "value": true
    }
]

License

MIT