ast-contains-only-empty-space

ast-contains-only-empty-space

Returns Boolean depending if passed AST contain only empty space

Table of Contents

• Install
• Use
• Rationale
• API
• Contributing
• Licence

Install

npm i ast-contains-only-empty-space

// consume via CommonJS require():
const containsOnlyEmptySpace = require("ast-contains-only-empty-space");
// or as an ES Module:
import containsOnlyEmptySpace from "ast-contains-only-empty-space";

Here's what you'll get:

Type	Key in package.json	Path	Size
Main export - CommonJS version, transpiled to ES5, contains require and module.exports	main	dist/ast-contains-only-empty-space.cjs.js	1 KB
ES module build that Webpack/Rollup understands. Untranspiled ES6 code with import/export.	module	dist/ast-contains-only-empty-space.esm.js	961 B
UMD build for browsers, transpiled, minified, containing iife's and has all dependencies baked-in	browser	dist/ast-contains-only-empty-space.umd.js	12 KB

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Use

const empty = require('ast-contains-only-empty-space')
...
// All values are empty, this means this object contains only empty space.
// Notice it's nested in an array, it does not matter.
console.log(empty([{ 'content': {} }]))
// => true

console.log(empty([{ 'tag': 'style' }]))
// => false

// Works on simple arrays as well:
console.log(empty(['   ', ' ']))
// => true

// Works on strings as well:
console.log(empty('   '))
// => true

// Object keys that have values as null are considered empty:
console.log(empty({a: null}))
// => true

// Works no matter how deeply nested input is:
console.log(empty(
  {
    a: [{
      x: {
        y: [
          {
            z: [
              '\n'
            ]
          }
        ]
      }
    }],
    b: ['\t\t\t  '],
    c: ['\n \n\n'],
    d: ['\t   ']
  }
))
// => true

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Rationale

Working with parsed HTML is always a battle against the white space. Often you need to know, does certain AST piece (object/array/whatever) contain anything real, or just an empty space. That's what this library is for.

In real life, parsed HTML trees will have many levels of nested arrays, objects and strings. While it's easy to check does a plain object contain only empty space ('\n', ' ', '\t', line break or a mix of thereof), it's not so easy when your object has arrays of empty objects. I want a solid, tested library which can identify emptiness (or lack of) in anything, nested or not nested.

By the way, weird things (like functions, which don't belong to parsed HTML structures) will yield a result false.

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API

Input - anything. Output - Boolean.

empty(input); // array, object or string — normally AST (which is array of nested objects/strings/arrays)
// => true/false

This library does not mutate the input arguments.

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Contributing

• If you see an error, raise an issue.
• If you want a new feature but can't code it up yourself, also raise an issue. Let's discuss it.
• If you tried to use this package, but something didn't work out, also raise an issue. We'll try to help.
• If you want to contribute some code, fork the monorepo via GitLab, then write code, then file a pull request on GitLab. We'll merge it in and release.

In monorepo, npm libraries are located in packages/ folder. Inside, the source code is located either in src/ folder (normal npm library) or in the root, cli.js (if it's a command line application).

The npm script "dev", the "dev": "rollup -c --dev --silent" builds the development version retaining all console.logs with row numbers. It's handy to have js-row-num-cli installed globally so you can automatically update the row numbers on all console.logs.

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Licence

MIT License

Copyright (c) 2015-2019 Roy Revelt and other contributors